I don't believe the manual is saying to hold the button any longer than necessary to keep the pilot going, which on both of mine is never over 10 seconds. I never put it on hi,....low only and walk away. They will sometimes puff a couple flames as I leave.
Both my wave 3 have oxy sensors on them, but they did discontinue them several years back, for 2 reasons, ...one, they will not operate above 6K elevation, but I have never verified that. Second, they don't need an oxygen sensor. Even w/o any windows open or any vents cracked, but just the normal (not very well sealed) Rv venting, neither of my heaters have ever attempted low oxy shutdown.
Then comes the safety issue,.....what makes people think that are going to die at nite when a cat heater is burning, and not die in the daytime under the same conditions ? But if you don't trust your cat heater to be on low all nite long to just keep the chill off, then don't do it,....it is you that looses the value.
Me, I cannot remember the last time I did not sleep all nite w/ at least one of my cats on low all nite.
Last I'll say, these heaters are great here in Quartzsite, but in high humidity, I still use them, but they make a lot of water on the windows.
Bought my first wave 3 in 1974, been burning them ever since.
The pads don't last forever, if dust dirt gets to them,....keep them covered when not in use.