I tried it and had that issue. Usually break time would happen while I really needed to keep my train of thought. Now I just try to do things in smaller sessions when possible and test often. While tests are running I go for a walk.

However, I have found it to be really nice for my Japanese language study. When I come back after a break I feel any new words or concepts I was learning have solidified a little better than if I were to just keep going.