I do an InReach message check every time I turn it on during the day or in the morning...and leave it off the rest of the time. Don't see dropped messages with that system. Also ensure I have a clear view of the sky when sending or looking to receive messages.
I do much the same. I have not had a missed message either. The clear view of the sky can be important - usually it works fine in the tent, but if it seems to be dragging I will put it outside the tent.
Surprised by the experience of 406. Most of the first hand failures I know of have been with the spot, not the Inreach.