Bob Michaels
nobody special
I think it makes sense to have a fast lens and a "walk about lens" in the fl where you do most of your shooting. For example, I use a Zeiss Ikon with the 35/1.2 Nokton in the evening, and a M7 with the 35/2 Summicron or 35/2.8 Summaron during the day. Same could apply to 50 mm, where one could use a compact collapsible lens for daylight and one of the fast lenses for the night and interiors.
I think it is all a function of your style. I could be shooting in the bright noon day sun and find myself shooting inside a dimly lit home 60 seconds later. And with no time to change lenses in between. Much less the issue of carrying extra equipment all day. Others have all the time in the world to shoot and not bothered with carrying loads of equipment all day.
So I am a bit of the extreme in usually choosing a lens in the morning before I walk out the door and making the best of my choice all day. My choices are based on focal length as I own very few duplicate lenses in similar focal lengths. But everyone is different and needs to do what works for them.