In my experience, the next day reserve preferencing is more of an annoyance to crew scheduling than anything else. Every time I tried it, they said they would have to check with some “planner”, you’d hear some murmuring in the background, and then get a polite no. They were short staffed when I was on reserve and were trying to always optimize open time usage, so your results may vary. My open time selections probably conflicted with their optimization goals.