Quick take
Use the coarsest micron rating that reliably protects downstream equipment, then increase housing/filter area when flow demand is high. A very fine small cartridge can create avoidable pressure drop.
Micron rating vs pressure
Finer filtration captures smaller particles but usually creates more resistance and loads faster.
Housing size matters
High-flow whole-house systems benefit from larger cartridge diameter and length because more surface area can reduce velocity and extend service life.
Stage coarse before fine
Heavy sand or grit can justify a spin-down or coarse stage before a finer disposable cartridge.
Watch the pressure differential
A falling downstream pressure reading under flow is a practical signal that the sediment stage may be loading, even before the replacement calendar says it is due.