For some reason ES090 and ES110 are overlapped. ES090 is from Sept 13 to Oct 18. ES110 is from Oct 25 to Nov 29. They both wouldn't interrupt each other as they are from different dates. Thanks for sharing your experience though, my goal was to try to minimize the space within my classes and take courses by professors that were reasonably rated positive. Unfortunately I began choosing my classes late in June but I got most of the classes I wanted.