The wider issue is that there is no path for someone who left say, as and SO2/ SO1 to rejoin as a 1 star or above.
There aren’t many SO2s and SO1s that stay that never make 1-star or above either. Also, how is the rest of the workforce going to feel if someone leaves because they can’t get promoted and then comes back 3+ ranks higher than them? Yes, there could be exceptions, but this should surely not be the norm? Also, with many exceptional characters not getting the chance to promote within the Service these days due to the bed-blocking introduced in the Regulars by MEOS at age 60, do you really think that getting gazzumped on the promotion board by someone coming in as a ‘lateral entry’ and taking your promotion slot is going to be popular? We are likely to lose more people over that than we gain...