Mine illuminates the TPMS dash indicator immediately if you "air down" to say 20psi. And off again the moment you air back up. Not sure what the true sampling rate is but its fairly close to real time. It shouldn't take any more than a key cycle or around the block at the most- that's as far as I went during my testing. It should NOT take 50 miles to illuminate.

 

the other thing i didntmention earlier is, if 10 degrees temp difference is about 1 psi, then why wouldnt the light go on wehn i set my tires tp 32psi when its 60 degrees f and its recently been -1 or zero. ill check again but i thought the manual said it goes off with 5 psi change.

 

Generally the tpms system is designed to go off around 20% below the manufacturer's listed cold inflation pressure ( where a tire is considered critically under inflated for its application )

That would be right around 5 psi in case, well a tad less than 20%.