I’m currently riding - GF Ti 2 with guards, dynamo and rack, 50/34 with a 13-32 (13, 14, 15, 16, 17, 19, 21,23, 26, 29, 32). That covers pretty well everything I need with a rack pack on. In the summer, if I’m fitter, I’ll ride a lighter bike with 52/36 and, preferably, 12-28, also 11 speed.
I also haves 2x10 setup with 50/34 and 13, 15, 17, 19, 21, 24, 28, 32, 36, 40. It’s a bit happy, but fine for long mixed days or carrying stuff.
Do I need 12, no. But I’m sure I’d find a way to use it...