If you’re wanting to do it by feel with a physical fader, my method won’t be of any help, but here’s what I do in that scenario (not using faders at all).
First, I make sure the volume of the drum bus group track’s fader is at the baseline volume I want.
Next, I go to the first section I want to raise (or lower) from the baseline, and add four automation points to the volume automation for that track – two slightly before the start of the section I want to raise/lower and two just afterward. How far before or after the section that will have a different volume depends on how long, and how smooth, I want the transition. For example, maybe there is a transition measure before the chorus and I want a smooth ramp over the course of that measure, or maybe I want the change to be more sudden (the latter could conceivably just use step automation instead of ramp automation, in which case maybe only one point at that end of the section would do).
Next, I select the two central points of those four points I’ve added, generally just typing in the new level I want in that section, though I could also deal with it with the mouse to raise (or lower) those. (If I want a ramp up or down in the course of the section, then each point would need to be adjusted separately.)
Finally, if I want to adjust the curve of the ramp at the start and/or end of the section, I’ll tweak the curve itself with the mouse.
Of course, after that, if there are more sections to do, I’ll rinse and repeat.
If I need to make changes later, for example to the whole drum bus level, preserving the basics of the changes, later, I’ll either use a VCA to raise/lower the level or just select all the automation nodes and type in a value however much higher or lower I want it to be in the field for that in the info line. I tend to use the VCA if I’m experimenting, possibly replacing it with the permanent changes once I’ve decided on any fixed amount of raising/lowering. Of course, it’s also possible to automate the VCA or manipulate any of the automation points directly if changes beyond just a fixed amount of raising/lowering of the whole automation are needed.
As for physical fader use, or automating virtual faders with mouse movements in real time, while I’ll sometimes do that, it’s rarer for me as I don’t feel like I have the same level of control (bad mouse/fader skills, maybe?) as I do by just entering values.
