Exhausting poops quickly (does it make sense to "oversize" my bath exhaust?)

Have a 30sf toilet/shower room adjacent to master bath. Want to make sure any fouls odors are exhausted as fast as possible to avoid them creeping into the bedroom area. I'm considering a 110 cfm fan with 4" duct, or possibly even a 130+ cfm with 6" duct.

Is it possible to go "too big" here? Is there a point where more cfm has diminishing returns on a small room like this?