Action Economy
If you are reading the Min/Max forums, it's safe to assume you've seen this term being tossed around (especially in the various Fighter threads that sometimes pop up). Most optimizers will have a loose grasp of this term's definition. The more dedicated optimizers will know what it means by heart.
The action economy is the number of actions you are able to take each round, weighed against the number of actions your enemies are able to take each round. For the average charactear, you have the following: 1 Full Round, 1 Swift, 1 Immediate, and unlimited Free actions. The Full Round action can be broken down into 1 Standard and 1 Move, or 2 Move actions.
Each of those actions has a different value for each class and build, and these values can change over the course of a single level up. A 12th level Wizard, for example, will be able to make greater use of the Standard action than a 12th level Fighter will through a single spell. Most of the pre-XPH classes aren't going to have much of a use for the Swift action, but a few of them will (especially if Complete Champion is allowed).
As with all economies, both real and theoretical, how you spend your portion of the Action Economy can affect the outcome of an encounter. A sign of a great optimizer is the ability to recognize which actions will affect the encounter with the most significance.
What does this have to do with healing? Everything. In combat healing has been proven highly inefficient for a number of reasons. The first is average damage outputs of the various common encounters. The second is the action economy.
In combat, odds are you can do more damage than you can heal. In combat, healing should only be used via passive abilities, such as Fast Healing. If recovering HP requires an action, you need to pause and weigh your options. Here's a couple of questions to ask yourself:
1: Can I survive another hit?
2: Am I within the enemy's Charge distance or melee reach?
3: Will an offensive action have a solid chance (55% and above, so don't rely on Crits) of ending the encounter?
4: Am I the one capable of doing the most damage?
5: Can I take an action that will prevent the enemy from taking actions safely (EG: Tripping them, casting Solid Fog or some other spell, repositioning yourself so the party tank is between you and the enemy)?
6: Will my healing abilities put me out of harm's way for more than one round.?
If you answer no to all 6 of those questions, then without a doubt you should try to heal as much HP as you can (consider one of those Minor Schema of Heal). If you answered Yes to even one of those questions, reconsider your actions. Try to take the action that will make all of the answers either Yes or No, not a mix of both. This is the key to healing in combat.
This is a very meta way of playing, and as such it may offend your DM. However, any character with a good Int/Wis should be capable of running through these questions with ease.
Here's a more in-depth look at those 6 questions:
Can I survive another hit?This question should apply to singular enemies, but ask it anyway if you are outnumbered. Look back at how much damage you've taken per attack. Compare those numbers to the number of enemies remaining. If your HP would be above that much damage, you can take a different action, possibly a more strategically offensive one. If not, do your best to reposition yourself before you heal, preferably without getting further injured along the way.
This question does not take into account Critical Hits. If your enemies outnumber you 5 to 1 and are all holding Scimitars, you should err towards the side of caution and consider each of those enemies 2 creatures. The same applies to mid-level combat: Odds are your enemies just charged you and couldn't take more than one attack last round. Take this into account.
Am I within the enemy's Charge distance or melee reach?This question usually applies after Battlefield Control is taken into account, when the closest enemy is still a good distance from you. If you are within an enemy's charge range, then you may very well be able to charge them first. If you are within their melee reach, odds are trying to heal up will provoke an attack and possibly leave you worse off than you were before trying to heal.
In both of those situations, it is more prudent to either be offensive (if you are the tank) or reposition yourself safely (if you are more squishy). Avoid attacks of opportunity as best as you can (Teleportation effects are great for this, but are usually a Standard action). Take into account difficult terrain and your own allies' melee reaches. Most enemies aren't going to charge you if they see a Paladin positioned between you and them.
Will an offensive action have a solid chance (55% and above, so don't rely on Crits) of ending the encounter?Let's face it: most classes don't have access to timely healing abilities. But something most classes do have is a damage output (if optimized). This question is effectively the inverse of the first one.
One thing to keep in mind when asking this question is the init order. If the enemy goes immediately after you do, it may be prudent to not risk an attack if you really need the HP and aren't guaranteed a killing blow (for example, if your odds of hitting it are below 75% or if you can't eek out that last 2HP of damage for some reaso). The same is true if you take your actions dead last, and he gets to go first.
Conversely if you know your attack won't kill it, but your allies all act after you do (but before it does), it's never a bad idea to just shot him.
Am I the one capable of doing the most damage?This is a bit odd to ask yourself, but is your damage output considerably higher than the rest of the party's? If so, odds are you will just get hit again after you heal up. In such cases, it's best to say something in character and have someone else use an action to heal you. Worst-case scenario, they attack the character who healed you. If that character survives the round, they may very well heal themselves (prompting the enemy to attack them again). This leaves you unchecked, allowing you to wail on the enemy for hurting your buddy.
Best-case scenario? The healing guarantees you another round, which is usually enough to finish an encounter if you are an optimized tank/glass cannon. Again, keep Init counts in mind with this question. If the enemy gets to act before your ally does, it may be wiser to use a minor healing item or ability to ensure you survive your enemy's next turn so you can be healed at all.
Can I take an action that will prevent the enemy from taking actions safely?This is the key to finishing off an encounter: Can your party's healer do more damage by healing you up, or by doing some Battlefield Control? In the case of an Artificer, you are almost always going to have a BC spell on hand, allowing you to buy time to heal the critically wounded or buff the party so they can kill the enemy without taking damage. Even a simple Move action can tip the battle in your favor: If they persue you, they may provoke attacks or move through difficult terrain. It helps if you are immune to the latter for various reasons, as it makes you more difficult to reach. Also, beware enemies with Ranged weapons when asking yourself this question (casting Grease does little good if the enemy Dragon just uses a Breath Weapon to attack you instead of getting up).
Will my healing abilities put me out of harm's way for more than one round? This should be fairly obvious, but in order to do damage you can't be spending your time healing up every round. In general, if your healing abilities will put you out of the kill-zone and keep you there for more than 1 round, it may be worth the action needed. Crusaders get an automatic point in this category, as their best healing abilities rely on attacking the enemy in question. If this is the case, you have my permission to use those healing abilities with impunity. This overlaps with the basic concept of passive healing abilities: A few weapon properties, the two Crusader Stances, and a couple other tricks rely on your offense, and act as a double-threat with regards to the Action Economy. These abilities are usually highly prized by optimizers.
Again, in combat healing is largely ineffective (until spells like Heal get involved). Because of this, the answer to all 6 of the above questions must be NO for you to have a good reason to use your Action Economy on healing. There is one other factor to take into acount here: The action required to heal up. This is the reason the Blessing of the Godless feat (above), the 9th level Devoted Spirit Strike (and it's two healing stances), and Healing Soul all rank so highly for in-combat healing: The actions they cost you don't usually interfere with your Standard/Full Round action, allowing you to maintain a constant offense while still recouping damage.
And, as I said above, you shouldn't build your character around healing. If anything, you should be focusing your character's build around preventing the need to heal (be it by sheer offensive abilities or through buffing your party to the point where most enemies can't do much damage).
