Hi biggiwant,
That sounds right because mitosis happens in the luteal phase. Missmadscientist has also suggested that we only need to be on BO from day 12 to 24. I read your BO thread and we have quite similar reactions to BO! (ovulation pain, spotting, growth in luteal, etc). BO is essentially ovarian tissue - it contains every type of ovarian hormones. Depending on when it's taken from a cow (nulliparous, estrus, given birth, etc), the content and ratio of those hormones might be different. You could find more info from the brand you get your BO from.
I want to answer GrowGirl's question again. Elevated levels of IGF1 (and other growth hormones) may cause cancer. It's not as risky as something like smoking cigarettes, but a link was found, although other research did not replicate the results or did not suggest a link. You should weigh the risks and use a moderate dose and be safe 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3614012/
I've also realized that I can't delete (my own) posts. Can someone help me with this? 