I'm going to be quite the hypocrite here, but I think n-1 is the optimal for some people and how I try (though rarely successful).

I've got a hybrid (bought when my road bike was stolen), a road bike (to replace my road bike that was stolen). I commuted to school on both, and commuted to work on gravel with the hybrid. Stopped using the road bike since Michigan roads suck.
Then, I got a hardtail, which could be good for snowy commutes but yet to try.
Finally, I got a gravel bike, to go on fast fast gravel rides with a group. I tried once on my hybrid and barely hung in there. Tried again on my gravel bike and hanging with the group was 25 beats/minute(heart rate) average easier! Now I want to commute on the gravel bike since I now experienced how much faster it is.

So... I want to commute with all of these bikes depending on weather and work location, but kind of wish I could get rid of them all except for the gravel bike and hardtail to simplify my apartment clutter.

N-1!! I've only sold 1 bike in my life, 1 stolen, and have 4 now. Selling is hard since there's so much emotional attachment.