How to know when you’re going to ovulate?

According to most opk products expected ovulation is with 24-48 hours after a positive opk result. However I downloaded the Premom app and it’s saying that you could potentially find your true peak by continuing to test after the first peak. And it’s like oh yeah other brands mistakenly say after a positive result is when you ovulate. I’m just sorta surprised because most OPK brands promote the idea that ovulation occurs after the first positive opk.

As opposed to Premom saying you can only truly know when your gonna ovulate by testing out the peak lh surge until the opk starts getting lighter. And then they’re like yeah when it’s light you’re the most fertile.