@Edward3c in all scenarios I witnessed, the mugging was done by diver not part of the buddy team.
regarding the HSE report, if it was done with professional divers, it has no direct correlation to recreational divers. It is a completely different world
@GlennL in both situations that I was mugged, the tanks were not empty but the divers thought they were out of air. One was due to a tank valve not being opened completely.
Regardless of frequency of checking, in training they are typically not pushed to a limit where they are truly stressed. It is a downside of most of the recreational training. In a cave, I will typically check my gas every 5-20 minutes. In open water, depending on tank size, I will check it every 20 minutes or more.
Part of gas planning for me says that I should check my gas in certain intervals based on depth and tank size. In sidemount for cave diving, I want to check my gas in intervals that roughly correlate to 600psi because that is what is convenient for thirds. With the LP121's that I dive in a cave that is roughly every 20 minutes when diving in a 100ft deep cave and when I'm on an AL80 stage, it's roughly every 6 minutes. That's a quick check to let me know that it is time to switch to the other tank in sidemount as well as making sure that I'm on track for my gas consumption. That goes up and down depending on my environment.
If that dive was a 60ft reef dive on an AL80, I would plan to check roughly every 1000psi which is roughly 20 minutes.
The frequency will decrease as you get more comfortable and stable with your diving and the environment you are in. Right now I'm on the tail end of conducting open water training. I'm diving double PST 130's, average depth of 20ft, and 3 dives per day of 30 minutes average. I only check my pressure when I set my gear up, and when I shut the tanks off for the night. I should be burning somewhere around 1500psi for that day and I check the gauges at the end of the day to verify.