Something shifts at 20 minutes exactly, anyone else ?

Good day fellow meditators!

I usually aim for 40 minutes to an hour per session. But almost every single time something shifts in my brain at around 20 minutes.

I don't get bored or agitated or like l've had enough. No, I can and usually do go on for another 20-30 minutes.

This subtle shift feels like something being switched off or on in my brain. And it's very precise time wise.

When I felt it today I even joked to myself "it's gonna be those 20 minutes isn't it, and then I go check my YouTube playing and it's at 19 minutes 50 seconds.

I gotta say - I dont always check, but every time I do - it is around those 20 minutes.

Does anyone experiences the same? I would love to know your thoughts. Thank you! 🙏