My son played in the WWBA with a team that had played together all summer and fall, and did well. We played teams that were put together for tournaments and for "special events" and it was a mixed bag. Yes, I believe there is a bond when you play with kids for a few months and you begin to know the player and know what to expect as well. However, if you have a core group of boys and add a few arms here and there I think you get the best of both worlds and I have seen those teams do very well in the big tournaments. It is impractical to think that your run-of-the-mill summer/fall team has enough pitching to go deep in the WWBA tournament with the number of games crammed into the number of days you play. It would be hard to keep the Pitchers satisfied during the summer or fall when you only ask them to play/pitch once a week a few innings, for your club.
The answer is to pick up an additional few arms to help with the pitching demnds of the BIG tournaments. They dont have to sit very long beofre they are asked to pitch and there may even be some other instances where they can get an AB or pinch run here or there with sometiumes two or three games per day for three or four days in a row .
So to answer your question from my experience I would say the answer to your question is C...a combination of the two options...