Also there is a fee to split the week, I believe it is $80 if you are not enrolled in the DC (same as lock off fee). Even when you own a resort that allows split week reservations, I don't think you can split and lock off, so split weeks are only available if you are using the entire unit for the two periods.
Using elected points you can split however you would like based on your points and availability at your resort or others. If you have a gold or platinum membership with II, you can do 2 short stays with a single deposit but inventory if quite limited. This could work in locations like Orlando where you could get two stays up to 6 nights each paying two short stay exchange fees. Locking off and making an exchange with each half would probably be easier and close to the same money even including the unit size upgrade fee but if you own a non lock off 2 or 3 bedroom it might be an option that works for you.