Fortunately, there's at least one PA calc out there that accounts for this, and optimizes for different DR levels.jgsugden said:For instance, if your foe has DR that you can not pierce, you need to reduce your effective damage by the DR when making your calculations.
...But unfortunately, it's not always clear when that is. Foes don't have "HP signs" floating over their heads. For the most part, it's best to ignore this effect.Another situation: If your foe is low on hit points, overkill damage is pointless, so power attacking, even though it will increase your damage, is a bad idea.
Which can be done.Another thing not often considered: If you expect to take AoOs, cleave off of high BAB attacks, etc ..., you need to factor those extra attacks into the equation....

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.