A typical low flow toilet flushes about 1.6 to 1.8gal these days.
Normal shower heads flow at about 2gpm.
1.6/2 = 0.8min, * 60sec/min = 48 seconds
Assuming that you are not effectively washing yourself while ijln the middle of waffle stomping. As long as you can waffle stomp in less than 48 seconds, it is a net gain for water usage.
It clogs easier as the shower drain is not designed the same as the toilet. Eventually it will clog and you will have to pay for a plumber. Get a fucking stool to use for squatting, they work great and will save you money.