Not very far. I get as close as I can get to him before I ever make a call, typically 75-125 yards depending on terrain and such. I see no benefit in calling to one way off unless one just wants to hear him gobble. At some point one has to determine if he/she wants to hear him gobble or kill him. I'll take the latter every time.
Long ways. I recall numerous birds 300, 400, 500+ yards across tilled fields and cattle pastures. Far enough away that I figured it's a long shot but what the heck...might as will get settled in and see what he'll do.
Generally I get as close as I possibly can before even setting up. However years ago I was hunting Chuck Swan and a bird kept answering me from across the lake. Nothing else was talking so out of boredom I played with him for 30 mins or so and to my surprise he flew across the lake and landed at 30 yards. He didn't make the trip back I'm not sure how far it was but may have been 1/2 mile. I argued jokingly at the check station he shouldn't count towards my quota tag because he was living on private property across the lake. They didn't see it the same as me
Might be my nemises bird I killed this past Friday. Got him to gobble from at least 500 yds with a looong series of yelps. Called only two more times and only moved maybe 75-100yds closer. I was in his domain and knew from hunting him so many times what he was going to do...if I just didn't call too much!
I called one off a bluff over a river a couple years back, he flew probably 7-800 yards off that bluff and landed about 100 yards away only to have a coyote run him off before he got to me
Called a bird across a wide open cattle pasture last year had to be 300 yards away when we saw him. Gobbled, half strutted and worked his way in to 30 yards. Fleet fox shot him