Yes, a close friend of mine was the service engineer for the main manufacturer of cremation furnaces in the UK. He worked all over the UK and sometimes I was with him.
A cremation takes at least 5 hours but they allow 8, then it takes 2 hours to cool down to the point where the oven can be opened and the bones crushed
It is all done automatically just like an oven on autotimer.
Crematoria have normally 3 furnaces per chapel , 1 actually cremating , 1 cooling and feeding bone crushing and 1 'spare' , the 3 are' rotated ' daily so that all 3 get the same amount of use.
Each furnace will 'feed'several crushers. Crushing is in a 'Ball mill' think huge tumble drier with a lot of very heavy steel balls inside, it rotates with the cremated bones until they are reduced to powder. the bones come out of the furnace as a recognisable 'skeleton' so have to be crushed to form 'ashes'
It is a 'production line' it has to be to cope with the demand, 64 cremations a day at each of the 3 crematoria near me. Try doing that with one furnace per body!