Hahaha, great question. Yes, there are rules to maximise getting curation rewards, but for me as a curator, i don't let timing deter me. i vote based on many factors and many times sift even the not-so-good for the good in it. Basically, curation is a talent too. Some people are good at it, some people study it, so it is subjective depending on the needs of the curator. timing parameters were put in place to many bot votes which are more perfectly timed than humans. for. Some people also target upvoting valuable comments too. Alot too has to do with amount of steempower and percentages. The best person to explain the timing aspect of it will be @timcliff