Anecdotally from some friends who are on reserve:

LCLs are always on the top of the list for full trips. They can pretty much count on being used for 3-4 day trips.

VECs will be perpetually on short call every day starting early and/or taking the early show trips with the 12 hour call out.

TRV seems like they will work the least compared to the other two. Again, anecdotally, it seems like TRV folks will work the least.