My approach...
1. SD game, dealt R06. If I am playing heads-up, I will play 2 spots all the time. This gives better penetration. Heads up, RO6, one spot gets 5 rounds of 2 hands (counting dealer), while heads up, RO6, two spots gets 4 rounds of 3 hands dealt, which is 2 additional hands.
2. Otherwise, I play one hand, particularly in DD and beyond, except when the count goes + and it is allowable to spread to two or more hands at that table. I do this to eat more of the good cards (greed).
I have seen some use multiple hands as a way of disguising their spread, but I've never tried this. Others use it as a way of getting to the "long term" 2x faster...