The minimum says most times 4 times 20 minutes divetime and the confined water sessions (where most times no minimum time is mentioned). So in 80 minutes you learn diving, and maybe 80 minutes pooltime in total. Do you think this is enough?
Also, if you have 10 hours total in water time, do you think all divers will learn the same with the same instructor? No, some divers are naturals and others are not as good as the ones with 10 hours after 30 hours.
Is the groupsize important? Yes of course, with 1:1 you will learn more than with 1:4. But it is not that you will learn 4 times more with a private instructor. Even the minutes no instructor is watching you, but you are in the water is practise time.
1 important thing in my eyes is bouyancy and trim. No skills on knees. The first time ok, but at the end, no. The instrutor must be able to be in trim, have perfect bouyancy, must be able to swim backwards to hold distance from students, etc. But to be honest, backwards swimming, bouyancy and trim are sadly no part of the instructor evaluation in most cases. So most owsi's don't know how to do. The last years it is slowly changing, but between what is written in the newer books and the reality is still that there is teached a lot on knees. Especially older instructors don't change anymore, they say 'we always did it right, so what we did is still right'.
Then, what is the best way to learn? CMAS clubs here say 'come to a club, it is getting slower, so it will be better', But is this true? A club here has 1 hour pooltime a week. So there are 5-7 confined modules in a cmas 1*. Every poolsession the student build his own gear together, so this is done 5-7 times before they go in open water. That is a good thing.
But the in water time? 20 minutes of a pool hour is spent with building the gear together. Also the last minutes to get out of the water. So if you are really lucky, you get 40 minutes in water time. So you have then with 5 sessions 200 minutes in water time. This is not directly divetime. It is also the time to discuss things. In our club these 5-7 sessions take the whole winter, 1 a month. So people also see their level going down because there is too much time between sessions.
Then the commercial 3 day course. Most divecenters that offer 3 day courses have or confined water as housereef, or have a pool that can be used the whole day. The first day is some theory and then the pool sessions. The 200 minutes is most times reached easy. Also skills can be repractised easy. But maybe the gear is not build together 5-7 times as you make longer sessions at once.
The open water dives for both, club and commercial course can be the same, 1 hour per dive, but in a club most times 1 dive a week, commercial 2 dives a day.
At the end, the total in water time is the same, the same is learned. The beginner with a cert needs then to go diving. Otherwise what you learned will be forgotten again.
What is better? If you are a natural, you will be on a higher level than average. If you don't have a lot of time, a commercial course will fit better to you.
The price is not cheaper if you do it over a club as they advertise sometimes. You need to buy your own wetsuit, fins and mask. And the fuel is not free to go to divesites or a pool and you pay a fee to be member of a club. A commerical course sounds expensive, but everything is included. So you don't need to buy stuff yourself, you can do after the course if you want.
Cmas is good for club feeling and divers with enough time. These are not the holiday divers. The level at the end is the same as from padi, ssi, etc. But their approach is different. No diving course is cheap if you don't have a sponsor.
And remember, there are not statistics that proof that padi is worser than ssi or better than cmas or that gue is better than sdi tdi or iantd. All divers have to deal with the same physics. All divers are human.
Standards are written by every agency and if you check them, most times they are all done at the end of the course. Landdrills are most times the hand signals, build your gear together. In water is most times a set of things like mask clearing, trim, bouyancy, searching for regulators, out of gas, etc.
Also a minimum in water time is mentioned. Some divecenters or instructors only do that minimum.
Also sometimes it is not very clear in standards what the level of skillperforming at the end must be. So some think 'the skill is done, so it is ok', others think 'the skill must be mastered, then it is ok'. And here a difference starts to grow.
Also the natural talent of a diver.
And don't forget the group dynamics. If you have a group with 4 divers and 1 is excellent and 3 are under average, the overal course is probably under average. Not because of the instructor is bad, but because the divers don't see a lot of the better diver, they see 3 students struggling more or less. If there is only 1 diver under average, this diver sees 3 over average divers and it is easier to follow them to get a higher level at the end. In group dynamics you have also personalities, do they fit or not? Etc.
So at the end of an open water course, a diver must be able to dive without a guide with his own buddy on the same level. This is written in standards. If this is what you want to see, most courses by divecenters that only offer guided diving are too low with this in the end as no single diver, even not the ones with over 3000 divers and instructors themselves are allowed to dive without their 'guides'.
After a course be able to dive without a guide will only be a level that is normal if every diver has to dive without a guide when they want.
But the level what you also see is 'Just don't drown under water' is for sure too low.
Diving in clear water means that it is easier to learn buoyancy. If you learn diving in murky waters, most times you are just 30 cm from the bottem. if you go to clear waters, these divers still are 30 cm from the bottom as this is what they are used to. It need time for them to get away from the bottom. With just 30 cm from the bottom and murky waters, a silt out created by you is not that bad as the viz is always bad. So the idea that you have to learn diving in murky waters as it is better is not true.
The ones that learn diving in clear waters can easier stay vertical in the water. So both have advantages and disadvantage, but there is not 1 thing better.
