to sand or not to sand (rivet detail)

Depends on size of rivets, and type.  Some rivets on kits are so big they look like rivets to assemble heavy steel boiler plates. If they are too big, I get rid of them

There are two types of rivets, conventional and flush.  Flush are used where streamlining is important and surface bumps would cause boundary layer seperation.  They were used mostly on wings and forward-most areas of fuselage.  These were almost invisible on painted surfaces, and were small, slight discolorations on bmf.

You need to do research to find which kind of rivets were where on each aircraft.  For rivets that may be too large, compare with photos of real plane.

I am in the minority that like some of the older kits with raised rivet detail. Many aircraft had quite numerous pronounced raised rivets on their construction. Some even still do today. Where appropriate I leave them be. Now on 1/72 kits of course they are going to be way over scale, and I would sand those down to where they were present, but just "barely there".