I go with 1 or 2 hen decoys with 1 jake or 1 non-threatening tom so I don't scare the shy toms. As long as you have 2 or 3 you'll be fine. There might be people that use more than that but it's not worth the trouble.

Big fat 0!!

All you need is a submissive posture hen.

I would say that it depends on the time of the season... During the early part of the season when gobblers are still sorting out the dominance hierarchic they will not pay as much attention to a hen decoy as they would say a submissive jake a strutting jake decoy. If you find where the dominant bird is roosting or strutting and set up in this area with a jake strutter decoy and crank out some jake yelps or fighting purrs, that dominant bird is as good as dead. If he's worth his spurs he will not stand for a young jake challenging him in his territory. Once they have broken up into flocks with gobblers and hens and a few jakes trailing as satellites, now its time for some hen decoys. A good plan on a big old dominant bird is to find where he and his hens are at mid morning to noon. They should be in a feeding or strutting zone. Get yourself in close to where they are without spooking them and DO NOT set up your decoy yet. Crank out some yelps and purrs and stay put. The boss tom will probably respond by gobbling but will not leave his hens. Keep him fired up for a while and then go silent. Still, stay put they will wander off. When they do go and set up your lone hen decoy facing you where the birds were responding to your calls. Towards noon his hens will leave him. However he will remember that lone hen that had him hot and bothered earlier in the day. When he comes to find her he will, he will also find a load of number 5's in his cranium. The key here is to be patient and still. Take a nap and he will wake you on his way back with some clucks or a gobble. Be listening and good luck.....