Not long ago we exchanged opinions re the "cold-cock Reset" of the Machine's sole-important 'memory'--er Image ..as is: Everything, post-Boot. Whether by push-button or otherwise:
I've taken to that method as 'preventive' (of such as you describe, to-a-Tee). Should I see in prospect the chores of n+1 [Refs], links embedded thence source sent to dev null, etc. [Transliterations--oh the Horreur!] I nuke the Image FIRST/cooling off even (in iMac case--via having been bitten as described, here), IWE: pull AC, let the always-ON stuff in PS box *also* get re-loaded, y'see?

I no 'stats' thus far; maybe this is just a chimerical postulate--but am willing to sacrifice the drill to Cthulhu, then.
One addition: after above, recently--thus the ~15 min-by-guesstimate w a i t before AC mains turned ON--the sucker was notably faster, verified by Activity Mon. and a peek at iStat as is indisppensable to moi. Thus shall I keep this koolaid on tap as, logic implies: yess-maybe: there IS a flaky component in this particular iMac PS/not dead-yet but ... needs Love every so often ... all that MTBF stuff, at work? ..it's an '09 model; ~~many of yours.

(Should this PS be proven flaky-as-described ... more often?) I should have to replace the unit, a real disassembly-POS on even 'repairable' iMacs: trouble-shooting 'intermittents' has always been in the orisons-via-tea-leaves category; there is only *rarely a smoking-junction discovered ... absolutamente--within my quarter century experience at Lab. R&R saves Time, lots. qed

* In the case of a Master EE-sleuth: ego.. may drive such a one to FIND that exact junction! But we know how That 'works', when you stop the clock ... maybe for days? I lazy.

Luck!