Snow depth, moisture content, slope gradient, floatation of your snoeshoes and your laden weight are all factors.
In demanding conditions, with 3 or 4 hikers, we change trailbreakers sometimes every 2-3 min, with the lead person stepping aside and filling in behind the train as it passes. This is for deep and heavy stuff on the steeps.
Fluffy snow or less of it, more often. If someone wants to break more 'cause they're feeling good, individuals can go longer. Its easy to burn out a frisky trailbreaker if left to do all the work, which can jeopardize the objective.
Mt Colvin from the Lake road in the summer is a couple of hours up at a moderate pace. 3 of in great shape took over 6 hours under deep heavy snow, sinking in 24" or more inches with stride.
This was a long way around the barn to say.....it depends.