The last two years we had a hovabator. We hand turned 3 times a day. We had x's and o's on the eggs and also a piece of paper handy just to mark what time we did them so the girls would know if it had been done or not. Essentially, it came down to...turn at 6am (right when the girls got up), turn between 2 and 4pm. (when I got home from work or called them), and turned at 10pm, essentially when we went to bed. We had "eggcelent" hatches.
towards the end of last year, I got a turner, but really we had too many eggs early in the spring to use the turner. we had different eggs too...ducks and chicken, pheasant, peacock..and they were all in the same bator at the same time. my girlfriend said she hadn't ever seen such an excellent hatch as peacocks were supposed to be hard to hatch and with hers, we got 95% hatch rate.
Of course, our bator was in the basement, where we live, its heated and in that office room, the ambient temp is pretty consistent year round. So, we don't have alot of varying room temps either.