When i use decoy's i use 1 jake and 1 feeding hen. Or sometimes just a lone feeding hen. I have a primos B-mobile but don't use it very often, has a tendency to scare away birds that aren't the dominant gobbler.
I'm going to run three decoys this year. Two hens (feeder, alert) and a jake. I feel the submissive hen is too low to the ground, and outside of the first week of the season (or in an ultra low cut or plowed field) basically useless. By the time the gobbler can even see it they are in shooting range. I'd opt for an alert hen for the visibility factor. I have had great success running an alert hen and jake over the last few seasons