Cloth, metal, mechanical, electronic, blade, old or new , expensive or cheap ? All quite different.
A good modern electronic shutter like in a F100 should not have more than max 1/4 stop at the fastest times ( 1/4000) and the very slow times,if at all.
Good mechanical shutters usually have a bit more tolerance, and are (as I was said once) mostly calibrated to work at 1/125sec absolutely correct.
Old or cheap shutters can have considerable tolerances and for slide film this issue can play a role indeed. One should test it with bracketing tobe sure.
Bertram