I've had 6 - twice into DUB (different flights), twice into SYD (same flight, eek), and twice into LCY (different flights). On my most recent LCY go around, I remarked to the crew member that I thought I'd had about 5 by that point, to which she replied that she'd been cabin crew for ten years and that had been her first!!
So, I guess the answer is they happen when they happen, and you may or may not be on board at the time!