Right or wrong, here is what I do:
• By default, every track output goes to Master.
• For things I want to control with one fader (like background choir), I mix all the tracks relative to each other and then rather than using a Send, I just set the output of each track to the group bus (like Female Harmonies, or whatever) rather than to Master.
• I personally do not send all drums to a separate bus because I typically like to tweak the individual volumes; however, people who compress or use other master drum effects commonly create a drum bus.
• I currently only use Send for effects like reverb, but in the past have used it to create special mixes for headsets or other things.
• I do not see any advantage to sending every track to a bus and then to Master, but maybe I am missing something.