C
Colour Republic
compression joint on copper is sometimes the best and only options in certain tight places, and or near joists...and commonly used in plumbing so you cant judge on that..but certainly the waste...I never use compression under or above..of course on traps you have no choice .
The times I use a compression joint or rather I HAVE to is maybe 100-1 (excusing valves etc). I can't see any reason for using compressions in the pictures given, other than the guy can't solder and he has never used solvent weld. So sadly my point still stands, that is no plumber!