Ovulation predictor kits

I've been reading Taking Charge of Your Fertility (FAM bible) and it says opks are a waste because by the time the test picks up the LH surge, it's too late (ovulation has already occured). Any one who is familiar with FAM and OPKs want to share their thoughts?? It seems OPKs are really popular on here, so I've been thinking of trying one but I also value Toni (the author) lol.