meh. I dont think doing gi helps you get use to anything except for gi. If anything, it teaches bad habits when training no gi. particularly in the guard and when trying to control you're opponent.
it's a lot harder to control you're opponent when you dont have a Gi to grab onto, so why get use to grabbing sleeves, collars, etc?
also there are a lot of gi techniques(setups for submissions, sweeps, etc) that wont work in no gi. So you're going to spend time and effort learning these techniques you wont be using with no gi when you could have spent that same time and effort learning/improving techniques you would use for no gi.
to the OP - if you want to fight mostly gi - train mostly gi.
If you want to fight mostly no gi - do more no gi.
If you want to do an equal of both then yeah train Gi for a while and then switch to doing no gi and gi.