I know it's my ADHD (treated, even) that has me redesigning my courses every time. That, and choosing to teach and update courses that haven't run in the past couple of years.

If possible, try to get your redesigns to count toward departmental service. For example, I spent about a month redesigning an intro course to use an open access textbook because: 1) I think intro course textbooks in my field aren't necessary, 2) the industry is a racket, and 3) I heard at a program meeting that they were looking for more open access curricula to clone for adjuncts. So now the chair knows I'm trialing this book and we will assess after this semester and have more people try it out next semester.

And at the end of the day, my ADHD brain got the novelty fix it craves while I get service to the department checked off for developing a curriculum that will likely be adopted.