I've always gone by the rule of thumb that E2 (estradiol) should be 150-200 per mature follicle, but has anyone ever found that their E2 is higher when their follicles are mature?

When the nurse called today she sounded a little confused because my E2 was at 211 so going by that I should be ready to O but my follicle was 14.7 and it didn't seem like I was there yet. Looking back at my IUI and IVF cycles, my E2 was more like 500 per mature follicle which would make more sense with the timing. Does this happen to anyone else?