On a holiday in Turkey I signed up for a AOW course. On the first dive I was buddied with the instructor and two experienced divers buddied together. For the first dive a limit of 50 bar was set for our return and we visited a wreck which being my first was great. Our depth was 20m and when I reached 50 bar I let my buddy know. He acknowledged the 50 bar reading but motioned for me to continue. When I reached 10 bar I reminded him but he indicated that he had plenty of air and for me to finish my tank. Only when I struggled to get air from my tank did he give over his octopus. We linked up but continued on going deeper and away from the boat and the dive continued for 20 minutes. I was relieved to get back to the boat and nothing was said. I don't think he had much English and if he did I couldn't see him using it anyway. I had mixed feelings about the dive as on the one hand I'd ran out of air and experienced that but then the guy was a bit reckless. What's standard practice in that scenario?