Look...its a matter of knowing where to make a difference to compliment the engine's appearance.
After doing it 5 years ago, the bodywork, and paint on the exhaust side of my bay has failed from the heat. Big chunks of slathered on filler, primer, and about 6 coats of black satin urethane are giving up the ghost because of the heat on that side.
Do I care about that?
Nope,....you can't see it anyway.
Knowing what I know now, I would've never obsessed about the frame rail caps, and all of the little nit-picky cracks and crevices that needed grinding/smoothing/filling/primering/sanding, when in the end, it can't or won't be seen anyway.
That still wouldn't have deterred me from the rest though.
Take my favorite engine compartment as an example, ( cause this was about as sleazy a job as I'll ever admit to)
All of this.......is a rattle can. The holes in the strut towers are filled with JB weld stick.
Compared to the current engine compartment paint that is now failing, ( and which took me weeks to do) this one is the result of a couple of days, and a lot of slight of hand. ( you can see the frame rail is stock, but your eyes wanna stay on the contrast)
Sanding cured JBweld stick is only slightly harder than body filler, and if you press that suff in the hole and put your finger on the back side to mushroom the goop that presses through, you form a "JB weld rivet " that will not want to fall out.
Now,....take your lazy asses to Oreillys, and buy some canned paint and a couple of those 8 dollar JB weld steel sticks, and quit being such a bunch of lazy assed weiners.