If this is actually following a formula, then it seems to be increasing by a factor of 60. 60 seconds in a minute. 60 minutes in an hour.
By this logic, panel 4 passes by at 60 hours per second, or 2.5 days.
Panel 5 equates to 150 days/second.
Panel 6 starts going into years, at roughly 24.66 years/second.
Panel 7... is 1,479.45 years/second. Almost 1.5 millenniums pass for each second they are watching.
Hilariously, the plastic does not degrade too much. The hall gets grittier but not sure if that's degradation or just tonal shift to show how jacked up this is. That first person, if she ever stops and goes back to her room is going to find all her furniture reduced to sand or something crazy lol.
At the same time... I'm wondering how this works for on the floor vs. outside the floor. Like, if you leave the floor it's like time never passed? Otherwise, this suggests the building has been for untold thousands of years. Then again, why bother trying to logic SCP-level stuff. This could be its own pocket dimension, like everything could be, for all we know hahahaha.