All depends on the track and size of jumps, etc...

There are some track layouts that I never break a single part... sometimes when learning a new layout that might have a large triple or quad and casing a large jump, I might snap an aluminum shock cap... I don't run the middle nor rear chassis braces, so I'll occasionally bend a center drive shaft. I think I bent a shock shaft once, never broke an arm, but the front arm holes tend to wallow out over time, and need to be replaced after about a year or so. After a nasty crash into a pole, I bent the front sway bar once... I usually go 2-3 months of racing before I might break a part after a weird situation. Maybe pick up a spare spur gear.... not a bad idea to check your mesh periodically, especially if you took a nasty cartwheel during a prior race, might be worth applying fresh thread lock on your motor mounts.

Best investment will be a pin replacement tool, I use this one:
https://www.amainhobbies.com/mugen-s...gb0541/p221425

I replace the pins in the driveshafts at the first hint of any flat spots... then you can expect your out drives to last indefinitely.