problem with having a ten part series is that if its a bit more on the divisive side i.e. futa or just not really interesting or anything, then you risk cutting out a bunch of customers. its a lot more risk
however i do think it could be pretty epic doing that, would take a lot of planning and stuff to get the story down tho
even just some more things that are two to four parts would be great, but you do cut people out a bit still, as they kind of need to buy all the bits