No you can it's not bad better to finish what your doing especially with the rtr as I heard that can leave gaps that allow hebrew curses to attach to you if you just stop mid way. (This would mean if you straight up get stopped with it for more than a few minutes you would want to start over and finish it asap) With meditations it's less of an issue say you are doing a certain number of reps of something on each chakra or aura cleaning or protection. You easily could continue where you left off there with no worry. If you get disturbed during a working best to start over on anything other than the planitary squares (if your disturbed for more than a few minutes) if your doing a square and get disturbed just remember what number you were on and do the rest for the day asap. It's mostly better to finish what your doing though. If you have to go faster ok.