Just finished my first two-gang switch box and finally have bathroom lights again

I had a similar nightmare in my guest bathroom last winter. Those deep plastic boxes always seem big enugh til you acutally try to fold 12-gauge Romex back into them. I ended up swapping my standard wire nuts for those Wago 221 lever connectors. They take up way less volume when you are trying to jam four neutrals and a pigtail into a crowded corner, and I find they give me more peace of mind than a massive tan wire nut that feels like it might pop off. One thing I learned the hard way after finishing my wiring was to check the depth of the switches against the drywall. If those grounds aren't tucked perfectly flat against the back of the box, the switches won't sit flush and your faceplate will look crooked. I spent an extra hour re-folding my ground wires with needle-nose pliers just to get that last quarter-inch of clearance. It sounds like you got the circuit logic down though; finding that line-side power is always the biggest hurdle.

I ran into a similar four-cable cluster when I renovated our powder room last spring. While grouping all those neutrals into one big nut works, I actually started separating my loads into different boxes when the volume gets that high. I found that even with a deep 22-cubic-inch box, shoving four 12/2 Romex cables plus switches in there puts a lot of stress on the terminal screws. I eventually had to pull it all back out becuase I was worried about a wire backing out of a screw terminal from all that pressure.

Now, I usually try to use a 'pigtail everythign' approach before I even mount the box to the stud. I make my lead wires about six inches long so I can fold them like an accordion. It takes longer on the front end, but it prevents that struggle of trying to tuck those stiff ground wires into the back corners without them touching the hot terminals on the side of the switch. I also started wrapping the sides of my switches with a few passes of Scotch Super 33+ electrical tape just as an extra layer of insurance against those crowded grounds.

I'm just starting to learn about this stuff and honestly the idea of pigtailing sounds a bit confusing. Is that better than just using the extra holes on the back of the switches? I saw some switches have those push-in connectors—could you just use those instead of a wire nut to save space? Also, you mentioned finding the 'juice,' but how do you actually tell wich wire is the live one safely? I don’t know much yet and I’m still pretty nervous about using a multimeter without accidentally zapping myself.