Maxibon,
As you rightly point out, this is extremely shoddy planning and a disgrace it has after all been going on for years. I had a year long hold lots of years ago. However, is generally only confined to aircrew specialisations and not across Airmen and Officer recruitment as whole.
The problem was not helped by the last SDSR, unlike some trades where you can be productive a few months after joining the RAF, the aircrew pipline is much longer which makes the manning levers slightly more difficult to control. Just a little bit of background info, but the fact remains, there is no excuse for 7 year holds!