Is tensioning necessary for #35 chain?

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Last season, we switched to chains on our robot partway through, and it caused us all sorts of problems because the wheel spacing was the worst possible (the chain was very loose, yet did not have enough slack to take off a half link) and we had problems with chains falling off. We would like to use chains next year, but avoid all those problems. From what I have heard, #35 chain is not very stretchable, and correctly calculating the center-center distance is sufficient. However, a mentor is still worried about stretching and recommended we add a chain tensioning system, which would add complexity to the chassis. What are your thoughts on adjustable tensioning with #35 chain? Worth it or not?