I never use 3F in my smoothbore, and in fact would use 1F more often if it was easy to get. I find the soft push of slower burning powder is less likely to blow a pattern than the more violent detonation of finer powder.
Hungry Horse
I believe there is quite likely a trade-off here, HHorse, between a 'softer' start and slower acceleration which would also have a higher muzzle pressure, against a faster start and lower muzzle pressure,
which might in itself, reduce pattern blowing, over-weighing the previous advantage and disadvantage. That is where the experimentation & testing of various load components comes in.
I an quite convinced, as with rifles, that a person could develop a tight shooting load with any of the powder granulations normally used in rifles or smoothbores, if enough load development/testing
was attempted, just as changing wads, powder charge and shot charge can have an effect with any particular granulation.
There is just about as much experimentation required to develop good shot loads, as there is to develop good rifle loads in any particular gun. As with rifles when someone who simply picks a load
out of their hat, they rarely grace the winner's circle at rendezvous- same goes for shooting shot loads - either when hunting or involved in clay bird shooting contests.