The one thing I wonder is this... on each subsequent journey does he meet a new/alternate version of Eddie, Jake, and Suze? Or does he end up drawing 3 totally different people from Earth(s)? I imagine each journey Roland makes creates a new/alternate timeline, which branches off from the prime timeline.
And as we all know (ala the butterfly effect), even the smallest change can cause a tremendous shift in a timeline (if you were to go back in history and change something). So maybe with the Horn of the Eld, Roland's subsequent journey took him on a totally different path. Heck, maybe Roland ended up drawing George Denbrough or Bobby Garfield this time instead of Jake.. maybe he will draw Carrie instead of Suze (that's an odd thought)... perhaps.. he may draw Charlie Decker instead of Eddie. I'd say Bobby, Carrie, and Decker are as troubled as any 3 people you could draw! haha