when I go out to shoot I usually bring my X100F and my SLR with a 55mm. that's about it. sometimes I feel 35 is too wide so I take those scenes I want a tighter crop on the 55. but generally yeah, my X100 is all I bring. I do feel like sometimes I'd want a different lens, but honestly there are so many subjects out there that it's fine to let some go. I know this camera and lens so well that I can shoot anything I want really quickly and to me that's the biggest advantage.
I don't have to fumble around and figure out where I need to stand to get my frame. I set my exposure and focus while walking up to a subject and be ready to take it as soon as I get there.
To me that's the biggest advantage to using mostly 1 camera and lens. you spend so much time with that camera that you know it in and out and all that stands between you and a shot is just clicking the shutter.