As I said earlier, the system used depends upon a number of factors. One of them is the purpose of the dive. Your post indicates you are spearfishing. In that case, it is important to separate the divers. I am sure it works fine.
In other cases--such as Cozumel--it is essential that the divers stay together. They will be diving as a group, which does not happen in spear fishing. Surface currents would mean that divers separating by too much on entry would have an extremely difficult time getting back together again. When I dived in the Galapagos, that was even more important because of more limited visibility, so we all backrolled at once with no air in the BCDs so that we could head straight down together.
So, yes, I do what the captain says. Are you saying that if you were in Cozumel or the Galapagos and did not like the method the captain calls for, you would ignore him and do whatever you want?[/QUOTE]
The method I described has nothing to do with spearfishing! I dive with my son all the time doing back rolls, again it has nothing to do with solo versus buddy diving. You seem to be somewhat ignorant about spearfishing as well. It is often done in pairs or even in a 3-man team.
And if a captain or crew told me to do something I considered stupid or dangerously stupid, I would NOT do it. I have seen many accidents, many stupid captains and way too many deaths while diving.
I once fell on top of a guy (while i was climbing a ladder). He had position himself too close under me while I was in a weakened state after a wetsuit dive in 45 degree water in New Jersey. I slipped/fell off the ladder in 4-6 ft seas - I still remember it well, I thought I might have killed Bill with that accident.
I felt terrible, the tank missed his head and slammed into his tank. It happened about 38 years ago. Even though it was HIS FAULT (for getting under a diver who is climbing a ladder)- I still remember how scared and bad (and guilty) I felt as I came crashing down on top of him. It was one of the more important dive accidents for me to be involved in. It left a very strong impression that there are good reasons for some simple protocols and that failure to follow them can kill people.
What seems to be missing from this discussion is that it doesn't matter who is "technically responsible". When someone gets killed or hurt, I feel bad. I try to implement procedures that reduce the chance of that happening.
So if a captain directed me to follow a protocol that I knew to be unsafe, I would get into the water in a safe manner... they way I want. I want to know for myself that the area below me is safe for me to roll into.