Some time ago, the RAF Puma force had reservist Pilots and Crewmen (I thing they were officially called auxillary at the time).
They were a real asset to the Sqn when Kosovo was running. They used to do 6 week detachments which gave the regular Sqn members a break from ops and also get on with prep for other tasks and exercises. It almost worked out that there was a reservist out there at any one time. Totally professional (there were all ex-regular) and committed. Life on the Sqn would have been a lot harder with more frequent detachments for the rest of us.
They also carried out a great deal of the more mundane tasks. They got paid, received operational bounty's but more importantly gained a great deal of respect from everyone else in the force.