A never-ending vicious cycle. As already stated, feast, famine, feats, famine. Many well put forward ideas and reason why for. Unfortunately, it is the nature of the beast without any easy solution. Retention has a multitude of problems when successful, significantly stagnation of promotion, gaining experience etc. Mind you the lack of retaining experience brings its own issues. My first posting, one Flight had a FLGOFF as the most experienced driver. Nothing wrong there but he was on the way out after a bit over two years at the SQN.
Why did we join. Well, you get some very first-class training, fly some nice pieces of kit, are with likeminded people (with some questions with some fellow winged wonders being perhaps the selection system had some hiccups, yes, I was likely one of them) and get paid to do it. So, the question is why did you leave? and there is a number of reasons. Interestingly first time I departed was interviewed on why by a budding WGCDR writing a thesis on aircrew departures. Gave a number of reasons, hopefully he got an A. Had another interview on retaining pilots when the Army (2007 I believe) lost 7 odd QHI in one week. This was when civvy contractors where all the rage. These seven chaps departed on a Friday, returned to work in civvy clothes on a Monday with a 30% pay increase, with hours Monday to Friday with none of the extra gaff (mind you the extra gaff is fine if you are after that first or second or third star).
I am afraid it is the nature of the beast. A bit like a Stando. For those of us that have been in one Squadron for some time we get to see the amendments put in by the new Stando, and the next one and the next one until SOP'S etc are back to if not the original form close to it (a good reason to have experience in the Squadron to say, "we did that three amendments ago, let's not waste the paper"). The nature of the beast with the thrusting young Officer making his mark.
I believe the book Sky Guardians, Britian's Air Defence 1918-1983 published 1993, addressed the retention issue in one of the chapters.
There is no easy nor hard answer I believe.