Minimum number of dives - perhaps 25
I had a discussion about using number of dives as a prerequisite to more advanced courses before. I believe the intention is to ensure that divers have a some competency before proceeding forward (e.g. OW to AOW).
Problem is, knowing the number of dives alone excludes the following info: were all the dives in calm conditions, does the diver have experience in challenging conditions (high current, low vis, cold, etc.), did the diver take a conscious effort to improve his skills on dives etc etc.
What does this mean? It means that a diver who is fast learner, keen and conscious may be a much better diver at 25 dives than your bo-chup, dive once a year holiday diver with 100+ dives. (The latter group, when coupled with the "photographer" category, can be especially destructive to the reef!)
Admittedly, gauging a diver's competency isn't easy. The most thorough way may be for an instructor to assess a diver underwater for trim, buoyancy control, safety checks, protocol and above water for diving knowledge on NDLs, narcosis etc, but this is certainly not practical for most people.
As there's a minimum number of dives requirement for PADI DM and AI courses, I have heard of some dive centres which get around this rule by getting their students to go through 10 minute shallow dives to "clock" the required number of dives.
So which is the greater evil? Imposing an arbitrary standard that only has some relation to actual requirement, or not imposing the arbitrary standard? I'm leaning towards the latter.