Your cat will tell us when they have had enough of the dryer.  Some cats love it, some really object to having the warm wind blow on them so we respect that and dry her as much as she will tolerate.  Especially after a full and difficult clip, some just get fed up with all the attention, so may not be 100% dry particularly around the back end and private parts.  The legs have the bone very close to the surface and gets hot for them, so we usually leave the cat to tidy up their boots.  Gives them the ‘last lick’ and helps them calm themselves.