Truly seasonal businesses have to do just that... Seaside towns for instance can really be in the doldrums during the winter; many businesses just shut down as the overheads can't be covered.
Some of 'the olds' in my family were in the restaurant trade. I can well remember how hectic things would get around Christmas/New year. As the caterers in the family were of Chinese descent the whole family seemed to shut down at the end of January into February for Chinese New Year... Often all the cousins would get hived off to the 'Gweilo' side of the family for much of the school holidays.. Then it would be quiet to middling for a few months building up to the great crescendo at Christmas again... Summer months were busy-ish....
Even my own business tends to ease off just before Christmas, gets busier as the weather improves, peaks around late October... I suspect relatively few businesses are without some sort of 'season' to them...