They "dance" for 90 seconds, 100 seconds in real competitions.

120 seconds of uninterrupted dance would be a strain even for good celebs.

I'm sure that most experienced dancers would think that if the celebs initially have around 100 hours one-to-one training with a top professional and, after that, cannot dance properly for a couple of minutes, they should take up fishing instead.
On the other hand, they then have to learn a new dance every week and that's not easy. Obviously the professionals know this and try to include in the choreography as many stairs, chairs, cannons and coffins as possible.
How long before all the gimmicks are exhausted?