Ok, so you have a car what needs some panel replacement and paint. Its stripped to the shell. At what point do you get the whole thing blasted ... before doing any panels, after doing the panels ???

You should blast first
And see what you have left to work with.
Sometimes what you think is good turns to
Swiss cheese..

well, here's where I see it.My friend is doing a 67 firebird resto. He knows it needs rear quarters, tail panel, trunk floor. he going to replace those then ship car to get blasted. if your not sure of areas are bad, grind down that area look for rust /bondo. You can pretty much tell what needs done before hand.Will those pin holes open up like he said ( swiss cheese) you bet.

i do it a few different ways depending on the customer. a lot of times I will blast twice or even three times depending on what kind of job they are doing.

blast the car.. needs quarters. cut the quarters now you have access to the wheelhouses and trunk extensions, clean those in the second blast. same goes for inner fenders, trunk floor ect.

some guys want the edm removed from replaced panels after replacement. quick reblast

some guys want the whole car done again once panels are replaced before epoxy

blast the car and find rust in the floors , remove the floor and blast inside the frame rails.

everybody has their own way of doing it. if your on a budget. I would remove your rusty stuff first then blast that should get the majority of the hard to reach spots. I would not replace panels before blasting as blasting allways turns up surprises.