In reply to Kean:
I am a keen diver and in diving there is the 'buddy system' too... all the usual checking of your buddy's tank valve, BCD straps, weights etc. Its quite ingrained in diving from the very start when one learns.
However, I am not a fan, personally. I can definitely see the use for people still learning, but I think that as someone who is reasonably proficient at something (diving, climbing, whatever), having your friend check for you is a bit of a crutch. If you're doing something potentially dangerous, you should be perfectly capable of doing your own checks; your life depends on it after all. I think that if you're not able to reliably tie your figure of 8, or turn your tank valve on, then you probably shouldn't be doing the activity independently (i.e. not under guidance).
Do we, as proficient car drivers, get our passenger to check if our seat belt is done up? Do we ask the person next to us at a zebra crossing to confirm the road is safe to cross? Probably not for most people.
Controversial perhaps, but its just my personal opinion and approach. However, I really enjoy solo activities such as mountaineering, winter expeditions, and remote hiking, and I have no problem popping into a wreck by myself if my dive buddy isn't up for it and wants to potter about outside.
However, on the flip side, I do believe there is great merit in fostering an environment where everyone and anyone can speak out, if one happens to be in a group. Its a big part of the safety culture at my work (oil & gas), and it can be very helpful; I try to promote it on my worksite as much as possible with things like open questions. I definitely see people more engaged and working safer when they are encouraged to speak up, rather than just me telling them what to do.