So I started with a perfect rust free car from 1972 and after welding in rear floors in passenger and trunk compartments, along with minor long repairs and new firewall pressings I continued to strip the car of all paint. Shocked I was that rust forms in foam filled cavities deep..but I digress. Wanting to ready the car for a new 911 suspension brakes and motor I chose to paint underside wheel wells, trunks, and interior first. This allowed me to reinstall things like bloer and fuel tank, front and rear suspension and hopefully soon the engine, over fresh paint, Bahia Red.

I still have the outer body doors and lids to finish, but plan to mask the interior. It seems sort of inside out, partly cause it is, but on the other hand I can now find the shop again, with parts going onto the car instead of taking up space. It is too late to change, or at least it will be a royal pita to try to change approach, but if there are problems with the approach, it would help to know what they are. As they say, to be forewarned is to have forearms, which would be good.
Thoughts?

I've used that approach. It works...

It may say something about me, but I've always painted the interior, wheel wells and done the underside first. It's the way my dad taught me, and I always figured it was a way to check how the paint would really look/stick/etc.

I paint from least important to most important which is typically inside out.

Eggzactly

Makes sense to me too.

I paint and then sand it off so I can paint it again. Kind of like th directions on the shampoo bottle

You dont want to potentially have overspray on your most seen area. I always pull the doors and hoods and spray the inside of the doors,jambs, and under the hoods first (And under the targa bar if I can remember). That way I can put the doors and hoods back on if I want and spray the rest of the car or leave them off and spray them at the same time (Depending on color/material).

FYI Spraying under the targa bar is a PITA and I prefer to do it the day before so if I touch the body I dont F' up my work.