Maybe once a year or so, I need to stop quickly while taxiing. Everey time I do I find it very uncomfortable for me, an d I'm wearing a full harness with inertia locking shoulder straps. If you're up and walking on MY aeroplane when I've got the seat belt signs on then you're on your own. It just ain't safe. Period.
If however you need to move about, then ask and I'll be pleased to give an honest answer. Remote holding while waiting for a slot delay, engines are shut down and signs are normally off. Long queue at the holding point, then maybe time for a very quick pee. One or two in front, then no way.