If it isn't obvious the question shouldn't be asked. Just put in a Bus rapid transit system, and change the line every few months until you find a "line" that is profitable, then keep that line going for a few years to prove it works long term. Now you have real rider numbers to plug into the equation of if the line is worth it.

I'm not sure rider number experiments are really needed. At least in MN rider predictions were on the conservative side, but reasonable as far as predictors.

Granted that doesn't mean your idea is bad or anything. I do wonder how many people would change their routine for a "temporary" bus line... not sure they would.

I think it was Portland (it was somewhere in the Pacific NW) in the 90's had a "custom bus" running late at night. If you lived within 2 miles of a regular bus route, you could phone in a request, and a dispatcher would make up a new bus line for that night that would pick up everyone who called in.

For public transit to work this is important. In the early hours of the morning few people want to get around typically. However the fear that you cannot get around if you need to holds people back. However if I know that should I need to there is an option that isn't too expensive I'm likely try it.

Minneapolis used to have a guaranteed ride home (might still do, I don't live there anymore) to cover people who took the bus somewhere, but had to work last.

Yup it is still a thing!

https://www.metrotransit.org/guaranteed-ride-home

That's a cool idea to cover those fringe events that aren't worth full time service, but you want to be there to help.