For me it dpends on the shisha. With SB i use 2 with a windcover.
For Nakhla I start out with 3, to get the shsiha going, then take off one and smoek with 2.
AF i use 3 usually, and don't use a windcover.
HH i use one.
These ar al in terms of 1/4 Exoticas by the way.