[cypher]

It really isn't necessary to do full cleans at all but you will need to do partial clean outs from time to time, a lot will depend on the hamster & how much it uses all the substrate by digging & burrowing, I keep dwarf hams which tend to burrow a lot so there are areas where a lot of food debris, dried poo & other bits & pieces tend to work down to the bottom of the cage & that does need cleaning out from time to time.
I generally just do about a third of the cage at any one time & always replace some of the old nest material or food hoard if I'm doing those areas.
I don't have a set schedule as it all depends on the individual & what they've been up to! I usually clean houses out every few weeks but always keep some of the old substrate & nest.
If you have a syrian that doesn't dig or burrow very much you may find you only need to clean the top layer & needn't worry about the rest too much.