A good thread.
I was teaching a couple of weeks ago an intermediate course (BSAC Sports Diver).
During the discussion. I reminded them there are two things you should be absolutely sure of before you step off the boat (quay/beach).
1. You can breath.
2. You can make yourself buoyant.
Failing to confirm those to things is unforgivable.
Before I do a buddy check with a buddy, I have already done a personal buddy check.
With regular buddies, it is not unknown if we are badly positioned on the boat that a face to face buddy check may not be done. But we all do personal buddy checks. The last thing that we always do before we step up to the gate, is ask, "gas on? buoyancy ok?"
The flicking needle thing, I teach. However, you need to have the cylinder valve almost closed. i.e 1/4 turn open (rather than fully open and a 1/4 back).
I've been caught myself, on a holiday charter boat. A deck hand turned my cylinder off, then back a half turn, after I had done the full buddy check whilst we where standing on the back of the boat waiting to enter. I think he was so used to turning the cylinders on for customers. I don't like people fiddling with my kit at the best of times. As I descended I was immediately aware of the restricting gas flow. I just pulled the set up my back and fully opened the valve, no problem.
Gareth