Both per- an de- can be used as intensifying prefixes. It seems that per- is far more common, but also de- occurs (detritus, defetisci, deplorare…). There is also deperire, where de- seems to intensify perire whereas per- is not really an intensifier of ire. There are some words that can be intensified with either prefix. I found vincere and populari, and I assume there is more.
I would like to compare these two prefixes. How can I guess which prefix is a more likely intensifier? Is there a difference in meaning between the two, either when both can be used or ruling out one? I know that both prefixes can also indicate direction, and in that case the difference is clear; my interest here is in intensification. Are there any general rules (of thumb) at all, or do I really need to go on a case-by-case basis here?
If giving a reasonable answer requires imposing some restrictions (only verbs and only in classical Latin, for example), feel free to do so. Also illuminating examples are good even without an overall theory. I am looking for some intuition into this thing, not any specific details.