One thing to note is that women with ovulatory cycles but with irregular cycle lengths, the greatest variation from cycle to cycle should be in the follicular phase. The luteal phase should be relatively constant (within 1-2 days). So if one has a cycle that ranges from 28-34 days, and a luteal phase of 14 days, ovulation would occur somewhere between days 14-20 -- not the middle of a cycle, not day 14 . . . This is the biggest mistake women with long cycles make when trying to conceive.