just check all oils before each meet and replace if needed. there is no rule of thumb every single combo is different and they all cop different types of abuse.
for instance we make 1200hp DOHC TT V8, rev over 8000rpm and change oils when needed, usually 3-5 meetings. apart from that absolutely no maintenance in between apart from usual fuel n water
the old 500hp 302W NA combo was pretty much the same, every few meetings, it was raced fortnightly revved to 8700rpm and rockers were checked once every so often
pump fuel you don't really want to let it sit for 3 months or more. race fuels, try under a year.