I do almost everything myself.
I use shops for stuff like
- truing wheels - I'll kludge it myself to get it working, but appreciate folks with years of experienceexperience taking it from there.
- Changing wheel bearings: I've done it myself a couple times, but it was a big PITA without the right tools.
- Facing a head tube if needed.
- Building a wheel.
- I will ship my rear shocks to someplace like PUSH or Fluid Focus for a full rebuild every few years - I do the regular air sleeve maintenance and seal changes myself, but I don't want to mess with the nitrogen in the dampers.
- I will ship a fork or shock out for a custom tuning... that is beyond my skill set.
Everything else I take care of myself. But there is nothing wrong with taking it in if you lack the time, skills, or interest in doing it yourself. That's what shops are for.