Edit 1: DC's seem to just be because of clears being too fast? even if you use auto kill waiting a minute or two before finishing the boss will prevent you from being booted. The same applies to things like Gate of Darkness. I assume there is a system in place that just auto boots anyone without a realistic clear time.
Edit 2: When reaching further stages this seems to become much less of a problem as even with auto kill and one hit ko to finish anything the auto doesn't, you come out of stages with a time slow enough to not be booted. Example is multiple runs of 5-6 and 6-1 with clear times of roughly 2 minutes and no dcing. Using speed hack may make you too fast however.