Compression effects combustion. End of story.
With commercial BP substitutes, compression appears to have little effect, but it does have an effect.
With real BP, compression has a much greater effect. With real BP, one has to decide what they want and act accordingly. Sounds simple, and therein is the problem.
Homemade BP comes out of the ball mill with the consistency of talcum powder. In this state, it is VERY EASILY IGNITED and due care is mandatory. From there, it is transferred to a compression die and put under several TONS pressure. The result is a thin hockey puck. In this state, it is VERY difficult to ignite, but if ignited, is VERY slow burning. It is the usage of various compression states, along with the addition of other chemicals for colors that is the basis for fireworks.
Now back to BP firearms. The hockey puck is broken up via screens/sieves to the desired granule (FFF) size. Compressing this charge has an effect. It is up to the individual to decide not only the granule size, but the compression of that granule.
Like anything else, there is always a trade off. Unless one is very careful, one can end up chasing their tail.
Chris