Where crank shaft and cam shaft seal housed

Does it need extra labor to replace
crank shaft and cam shaft seals
besides of head gasket? Mechanic
counted 4.5 hrs for head gasket and
3.5 for crank/cam shaft seals. I think
once mechanic opens the head
gasket, the cam/crank shaft seal
should not take more than half an
hour as they are housed in the same
place as the head gasket.