When we were traveling first thing I did when we were going to be pulling out in the morning was go turn on the monitor. As I was putting the various things away and loading up the trailer/truck I would look in and check the monitor for all readings and once they were showing, maybe as long as 4 minutes from turning the unit on, I knew before we pulled out how all tires were looking. Something that has been talked about in the past is the sender making good contact with the valve stem valve. Some stems are screwed down into the valve stem a tad too far, not giving the sender a good flow and that makes the sender read sporadically or not at all. When I first installed my system years ago I needed to adjust the stems on at least 2 or 3 tires to get a solid flow to the sender for a good signal. I ended up purchasing a repeater and found that the amplified signal was so good I could get my monitor to read all tires from as far away as almost a foot ball field. But without that repeater I could still read my tires on the rig while moving down the highway. I have helped may other TPMS owners get their systems working correctly by playing with the valve stem valve.