One for the aviation safety experts here...

I was pondering this the other day after I landed. What is the reason for keeping your belt fastened once you've landed and have cleared the active runway (i.e. so there's no chance of a go-around)? I mean, to me, I'd have thought that taking the belt off once you're down is far more sensible - surely every millisecond counts trying to get out should something happen on the ground for example. Based on the same reasoning that pilots often announce you should not fasten your belt until re-fuelling has completed on the ground and he's turned the seatbelt light on.

Remain seated, etc. all makes perfect sense. So is 'with your seatbelts fastened' just a way to try and more easily enforce this?

Phil