Ovulation test or CM?

Please don’t think of judging or rude I’m just trying to understand.

So why do sooo many girls recommend and go by tests to find out when you’re ovulating? Like you pay money to pee on a test to let you know when you ovulate?

Why?

Our CM tell us, for free.

What’s more accurate a pee test or your body literally changing its consistency when you become fertile.

It’s only annoying me because glow won’t change and update my ovulation days when I tell it my CM. Everyone keeps saying to take a OPK TEST and glow will update according to the results.

I just don’t want to pay $30+ for a box of tests when I KNOW when I’m ovulating because my body is telling me so.

Why can’t glow understand that.