Not OP but I also have a timer for certain social media apps, including Facebook.
For me, the timer is just there to remind me X minutes have passed. Losing track of time while doing something, anything feels natural to me. It happens in real life when I stumble upon a friend on the street and we start chatting and it happens in social media when I scroll too much.
If I'm reading something and my time is up, I just extend that and able to close the app afterward.