Hi Jill, I've been using the CBFM for almost a year, and it always gives me at least one high day (two bars), then always two peak days (three bars w/ egg), and then another high day. I think that what I've learned is that basically when you get the first high day, it's just giving you a heads up that you'll be ovulating very soon. Then on the first peak day, it's telling you that you will ovulate within 24 hours or so. Then it stays peak one more day for good measure, and then goes back down to high after that, because you are still potentially fertile in that time period, since the egg sticks around for a little while after it's released.
I agree with Sunshine: the iPhone app, though good for tracking things like cycle length, is definitely not personalized for ovulation. My iPhone app says that I"m supposed to ovulate every month on 14 dpo. But I ovulate sometimes on 8 dpo, and sometimes on 18 dpo. So I too would recommend sticking with the CBFM for that. Hope that helps! Good luck!!!