I have no idea what you mean.
If it takes six months in total to finish one route, and there are five routes, the game will take thirty months to finish regardless of what order you do the work in.
That's highly simplified, of course. There's common work like Maria, and you might get a small concentration boost from doing one at a time for as long as you can before having to take a break, and there are external artists to coordinate schedules with, all of which might put constraints on the schedule. But it's not obvious that running each route to completion will result in the entire project finishing faster. If you think this is true, I would appreciate an explanation.
So pretend Dyne does work one entire route at a time, and the only route I like is Chester, and Chester is last. I would be much happier and stay more interested if I get a day every couple months like I do now, than I would be getting *nothing* for years, during which time I'd probably forget the project entirely.
And yes, it's a patreon project. No one has incentive to pay unless a character they like is being worked on.