Keg pressure question

Beginner kegger, I have my beer in a corny for 5 days at 10PSI @ 35-40 degrees in my cellar hatchway. On day 5 I sampled a beer, nice had a good foamy head.

Then I put the pressure down to 5PSI figuring I would get it to serving pressure for the weekend. On Friday (2 days at 5PSI) it was somewhat flat.

I was under the impression that one keeps at 10PSI until carbonated, then you can dial back to 5PSI for serving, and leave it at 5PSI?

Or after serving bump back up to 10PSI?

5 psi seems low even for serving i put mine at 12 psi and serve at the same.

Get the whole carbing pressure and serving pressure thing out of your mind.

At about 38F and 10psi, you'd reach 2.4 volumes of CO2 in about 16 days. If you want to maintain that amount of carbonation, you have to leave it at 10psi until the keg is empty.