The magnets were in fact giving me gas!!
The instructions say in theory the more you have the better the resolution will be for control.
But some setups only require two, some 4, and some 6.
It depends on how big your gear is you are mounting to.
If the gear is to small you can get overlapping magnetic fields and it will mess up the hall sensor.
I tried 4 at first and it did not seem to work well.
It was also hard (at least for me) to get the N and S correct on a cube magnet.
You have to stagger them NSNS on the gear.
It was hard with the different sized magnets to get the polarity correct.
They give you two small and two larger magnets.
The two seem to give me as much precise control as I need for my set up. BD.