I hope you will conclude that the only guarantee against a mishap is eliminating a partially open condition. Once you've done so, a few breaths off your reg and you will have absolute surety that barring a separate failure, your regs will deliver air at depth.
Rather than become a POV warrior for my new practice, I think I'll leave it at that in this thread.
Thanks to all for helping me reset my priorities.
Yeah, I'm with you on this one. I simply don't understand why it needs to be more complex than open the valve, and take a few breathes from both second stages while watching your spg.
Making allowances for people who can't figure out which way to turn a valve to open just seems like bad practice. Saying that some new divers can't remember how to open a valve is like saying that some new divers can't remember how to watch depth, time or tank pressure. If that's the case, they simply shouldn't be scuba diving beyond a DSD class. I don't think that's asking too much.
Unless you are diving a CCR, open the valve all the way.