I've read this thread a couple of times, and going back to the actual question asked by the OP, I think the worst "bad habit" one gets into with experience is complacency. It's easy, as you get more accustomed to diving, to forget that we can't breathe water, and that safety things are taught because they're IMPORTANT. I got a good reminder of that when we were in Cozumel. We were getting ready on the boat, and the DM had gotten into the water to check currents. He came up and said things were fine, and told us to get in the water. We hadn't finished our equipment checks, but I began to abbreviate things because I felt obligated to follow his commands. One of my buddies stopped me and told me to tell the DM to hold, and we finished our checks.
He was right -- We do those things for a REASON, and it's because making sure everything works correctly before we get in the water is a way to make sure the dive proceeds uneventfully and enjoyably for everybody. The day you don't check stuff is the day you'll jump in the water with your valve closed, or something equally bad.
He was right -- We do those things for a REASON, and it's because making sure everything works correctly before we get in the water is a way to make sure the dive proceeds uneventfully and enjoyably for everybody. The day you don't check stuff is the day you'll jump in the water with your valve closed, or something equally bad.