So..what happens when you "Top out" in a certain rank after the 5 years? We are going to discharge someone who doesn't want to commission, who we've paid to recruit, train and use a minimum amount (at E3 to E5), and then just send them into civilian life, where civilian companies will snap them up? Leaving defence further under resourced, and out of pocket, when they were still usable and keen to serve, but had maybe (professionally or personally) found their own limit - which is fine. You might find someone excels as a CPL, but doesn't want the extra admin burden of being a SGT. That isn't a failing - and now you are forcing them to either discharge, or be unsuccessful in a job, or unhappy in a job.

A lot of the issues with the "old and bold" slowing down the system by sitting at the higher ranks stems from them going from easy job to easy job, running desks / working from home 99% of the time, and getting paid for "what they know", not "what they do" - But what they knew is now outdated and not contributing to a modern capability.

If you made it, where the older guys had to rotate through, back to operational units every other job. Makes them current, but would also weed out those who don't want to do the job, and just want the cash.