What do people generally do between dives regarding turning off and purging? The risk being just turning off and then not turning on again. You put it back on, breath it for a while and it maintains 0.7 for long enough to fool you, you jump in the water, don’t look at the handset for a bit and go hypoxic swimming to the shot line.
With wireless transmitters it gets habitual to turn valves off and purge after diving to save transmitter batteries.
Predive, you open the valves and see that your transmitters activate, then cross check with SPG:s. During prebreathe and surface swim monitor that they hold pressure.
It doesn't protect if you don't look at handsets at all, but in my opinion having an electronic pressure sensor with alarm on O2 does add some margin against closed O2 valves on the surface. Most people don't routinely dig out the SPGs at the shot before descending, but they are more likely to check their computers.