The answers to the questions you are asking are very much dependent on the situation at hand, as well as personal preference.
There is no "right" way to do it. What ever it is that gives you the results you seek and sounds the best is the right way.
Perhaps the reason metallica record the bass later is because that's the way the bassist likes to do it.

And there could be any number of reasons why Def Leppard do it the way they do it, but each band and each member, for that matter, might have their own preferences for god knows what reason.
In that case, you need to be flexible because your clients are going to have preferences, and they are paying you not only to get them a killer sound, but also to make their life easier.
If tracking a certain way helps the band to feel at ease and brings out a better performance or makes things run smoothly for them, than it is the right way.
But if you get lucky enough to have it your way, then 9 times out of 10, you should have them track the drums and bass first -- together if at all possible, because then they can play off of each other visually. Have the singer and guitar player play scratch tracks over the headdphones for them. Record those, too, if you'd like, just in case you get some keeper tracks. Then overdub everything else one at a time.