Here is my typical set of buses:
Master
Vocal Reverb
Drum Reverb
Instrument Reverb
Backing Vocals, if present. (If there are male and female backing vocals, I have a bus for each.)
String (or Orchestra), if present
A drum bass makes complete sense. I just don't do it because I typically find myself tweaking the individual levels (e.g., kick, hat) more than the overall level, but I probably should use a drum bus and may in the future. It especially makes sense for live drums that may need compression, something I seldom use on sampled drums (but again, I am probably in the minority on that).
I don't create buses for single instruments or small groups of instruments because it just seems like more complication, more faders, and more signal path. Plus, on my console, I have to switch between track and bus views—the same physical faders control tracks and buses—and it is not convenient to switch views to adjust a single instrument.
The advantage to everything routed to buses is that you can bring the overall levels up and down in a single view, but for me, that hasn't been worth the complexity.