For "everyday" photography, I've used a 35mm (FF) as my "one lens" for years, and for the last 10 years or so a 35mm equivalent on a Fuji X100s. My "standard" lens on medium format and large format has also always been a 35mm equivalent. (Pimarly landscape)
For everyday photography, I like having a 35 and a 50 available, I generally prefer the 50, but find it not wide enough to be a single lens. I'm also beginning to prefer the 50 for landscape, which is a little strange after around 50 years of preferring a 35mm.
I'm seriously considering a 40mm, but wonder whether that will turn out to be neither one thing nor the other.
I think two lenses is the "ideal" and with higher resolution sensors, I might think about a 28mm + 50mm or maybe a 28mm + 40mm as an ideal minimal carry.
I tend not to change lenses very much, I seem to only change when I feel forced to, and then tend to carry on for the rest of the day using the lens I just changed to.
Having said that I've also had periods using a 24-70, 24-120 ,28-200, and the equivalent of a 24-400 zoom as my one len. With the zooms, I love the convenience but hate the experience,
An interest in wildlife means the longer zooms are handy to grab the occasional dragonfly/insect photo to help with it;s identification. I haven't yet come up with the ideal solution for this.