are clearblue advanced ovulation tests dependable

my husband and I started using clearblue advanced ovulation tests for a couple days now and the first two days i got low fertility. and the third to fifth day it showed i had high fertility. my husband and I are ttc our 2nd baby and were wondering if anyone else has had more than 4 fertile days and still conceived. i saw someone's post yesterday about how she had so many high fertility days in a row and that she stopped wanting to use the clearblue advanced ovulation tests b/c she felt it wasn't working for her. we started thinking about what if we dont get our peak fertility and all we keep getting is high fertility?!