I agree in theory, but - merely increasing a charge of X powder by 10% and calling that 'OK' is not the way to do it for the private handloader.

Pressure equipment in a Lab is needed and that 'proof' load must be worked up to using such equipment. Much depends on the exact powder being used as some become unstable as pressure climbs above a certain level. This can cause pressure 'spikes'. Case capacity and shape come into the situation as well. Pressure spikes are to be avoided, but can happen with a very small increases in powder charge, below 10%.

Many smokeless powders do not react in a linear fashion and rules of thumb can get you into a world of hurt.