no timing is not critical at all, many LARGE studies have found absolutely no link between timing and gender. I can only think of one study other than Shettles own study (which, for the record, wasn't even scientific as he was getting the women to do other things known to sway too such as douching, diet, clomid not to mention he had a flawed theory) that found a link so most likely that one was a coincidence. The majority of studies have either found no timing link or a very slight trend in the opposite way (more girls conceived at OV).
when you're looking at smaller groups or people you know luck plays a more significant role. Most people don't even have any idea when they OV - perhaps those who think they OV on CD14 and DTD on CD10 actually happen to OV on CD10 because most women don't OV on CD14. Even if using OPKs they can't know if they have already OVed by the time they get the positive (and have caught the end as the LH surge is dropping) or if they will OV 3 days later. This makes any testimonial from someone you know quite irrelevant.

