Personally, I like Walk-Around type publications when I'm working on something, but have also used a print of instrument panel pictures to get the right gauges in the right place. I dug pretty deep into the ACH-47 conversion, mainly using two walk-around type books, and personal photos.
In the process of a super detailed Titanic dio at the present time, and even though their are some excellent books available (I purchased four), I couldn't have done it without three or four GREAT Titanic modeling sites.
When I "do one up", I usually build a while and look a while, until I can no longer recognize anything glaringly different. It seems with me, one correction or PE application spawns an adjacent fix... which spawns yet another, and another. After a certain point, I have so much time wrapped up in it that I feel compelled to go for it.... strangely though, ?, after I complete one, I rarely ever touch it again.
I'm no rivet counter either... I guess the old "how much is enough" question is dependent on how much time we have to put into a build, and most importantly, when the Builder is happy with it!
If that's accomplished, it's been a successful build.
Take care,
Frank