This is really annoying for me, how can I work for a full financial year (and get my shares allocated), receive my performance review but not get a bonus because I quit before October where they pay the bonuses on the last FY?

Hence the wave of resignations the week of bonus payouts. People play the game and wait to get paid, knowing if they prematurely signal their departure, the company will reallocate money to those who choose to stay. I'm not saying it's right but it happens.

And then you only get half a bonus at your new role if you are lucky (my last job I joined 3 days too late to be eligible)