I remember when I first signed up for a standard 2 weekend OW course. An acquaintance mentioned he'd taken a monthlong diving course many years ago and then lost interest. I couldn't wrap my head around spending a whole month just learning how to dive. I probably wouldn't have signed up for that. By now I've probably had close to that much instruction (and more dives in the last year than I probably expected to do in a lifetime) and I'm looking forward to spending my whole summer on another course.
A higher bar for entry might improve retention rates by keeping out the riffraff who just want a taste. But some of us riffraffers might surprise you and come back for seconds.
It does depend on what the course content was in that longer course. My OW class is 6-8 weeks once a week with half the session in the classroom and half in the pool. The student ends up with somewhere between 12 and 14 hours in each. In the first session they don't even put a SCUBA unit on. It's all swimming, snorkeling, and breath-hold diving skills. That is also where they learn mask clear, fin techniques, and the fundamentals of buoyancy and trim using proper weighting and lung volume control.
Some people do get it quickly. Many don't. I want to see at least a dozen mask remove and replacements while swimming and doing other tasks. Along with reg recovery, weight adjustment and remove/replace, etc.
We do a complete gear remove and replace and exchange in the OW class. There are also rescue skills included. Panicked diver at the surface, non-responsive diver from depth, rescue tow while stripping gear, and supporting a diver at the surface and helping them achieve positive buoyancy.
All skills are done neutral and horizontal. No kneeling.
We cover emergency decompression tables using the US Navy air dive tables and I spend one classroom session solely on gas management.
Since we are in an area where vis can get bad on checkout dives, one pool session is spent on skills with eyes closed or using a blacked-out mask.
I don't take my OW students on checkouts unless I am 100% certain that if I have a problem, they can safely assist me and end the dive.
At the end of checkouts before I give them their card there are two questions I need to answer.
Would I dive with them and be certain they would be a good buddy and be able to help me if I had a problem, and would I allow my kids, wife, girlfriend, or anyone else I care about to dive with them without me or another dive professional present? Knowing they will be ok. Only then will I give them a card.
If they meet all the standards, do great on checkouts, and then say to me something that makes me think they would not be safe or be a danger to others, they don't get a card and the agency will back me up on this. In fact, it's in the standards that we have to be satisfied they will be a safe diver and good buddy.
It's called the "loved one principle" and it has seen some of my students have to do additional checkouts because the comfort level in the pool doesn't always transfer to OW with limited vis, cooler temps, and marine life.
I don't have time limits on my class and people need to meet my standards as well as the agency ones.