It depends on the model and camsite.
A dollar is a dollar to me, so I'm fine with 1-2 min shows - on certain camsites. They don't negatively affect my bottom line on sites like Skyprivate; or Streamate, where there's usually only 5-10 logged in members watching at most, but if the same were to happen on a token site like CB or MFC, it cuts down traffic by half and ruins the momentum of shows, taking a while to build it up again.
The average show for me on SM is 10 mins, which I'm happy with! It keeps things fresh and interesting, which helps my energy levels, as no two privates are exactly alike, and so if 3 people do a 10-15min show with me per hour, I'm very fulfilled and look back on the hour fondly.
There's also such a thing as being too long
The longest I ever did was 1.5 hours, and while I had a great time, it's too exhausting to do more than once in a blue moon. Seeing the earnings from it was almost unbelievable and I'm grateful anyone would be willing to spend on such a long private, but no amount of money could make up for the quick burnout it would put me on.
I used to regularly accept prepaid one hour shows for one man in particular. Absolutely great guy, so I felt terrible to explain that I just couldn't do more than 30 mins after doing it so regularly. It would honestly give me anxiety in the hours leading up to the private, even though we got on very well and had great banter/actual mutual masturbation ratio, but I'd have to frequently postpone because I knew how much energy it would take.
So to end this tangent, longer shows =/= more worth it, if anything it's a good way to burn yourself out over the long run as a model.
Members, I don't think you should feel bad or worry. Simply as if they're okay with x or xx amount of mins of private, and if they say yes, it's OK!