IMHO you are "ready" if you practice regularly. This means you need at least one other like-minded individual - your dive buddy. Ideally you have a whole bunch of like-minded divers in the area. Near the end of a dive when we are doing our safety stop I often signal my buddy YOU-WATCH-ME. He then knows that I am going to have some type of mishap. I usually go OOA. Next, I signal I-WATCH-YOU. So, he goes OOA. Sometimes for a change (where the bottom is at about 15-20 ft) I dump the air from my BC and sink down the the bottom where I lie "unconscious." When my kids start to dive and after they learn to do a rescue I plan to have a heart attack on every second dive
Edit: MikeBell, welcome to SB!
That is both excellent and terrible! Haha That's great, if I had a much more experienced buddy who was able to do that, I would welcome it. Getting used to dealing with those situations, real or not would be great. I would like to get to a level in which there is no panic, only action. Also, thanks for the welcome
Back to the ready comment, I meant more about AOW classes. I think classes are the most ideal to become "ready". They are still controlled (to an extent). You have 1 or 2 or however many senior divers with you to help you through issues and answers to questions you may have. I felt more comfortable on my dives after my OW certification because they were with senior divers and I was able to further practice some skills.
Everybody could be "ready". It just takes training and repetition. The problem is that people tend to not get much of either.
I would agree, even from my limited experience. Dive often, safely and within your experience level. I was glad to take my AOW class two weeks after my OW class. It was worth it for me, it solidified some skills that I would have forgotten if I didn't dive for a month+ afterwards.
How do you know when you are "ready" ..
- when taking a reg out of your mouth and replacing it with a different reg isn't a big deal
- when removing and replacing your mask isn't something you dread
- when you can ascend while sharing air, maintain a controlled ascent rate, and stop when you want to
- when you can stop and maintain your buoyancy without finning
- when you can descend without crashing into the bottom and consistently hold your safety stop on the ascent
... then you are (minimally) "ready" to progress from OW to whatever next class you should choose ... these are all skills you supposedly "mastered" in your OW class ...
... Bob (Grateful Diver)
Yes, that's the plan right? but for myself (and a number of other people) you learn through repetition. Then you question, is 5 dives enough for the OW cert? From your above post - I would say no way. I'm not sure of many people who "master" those skills in their OW class. Would PADI change the requirements? I doubt it, which leads into placing divers with OW certs that aren't comfortable in the water.
For me - Reg replacement wasn't a big deal, stopping and maintaining buoyancy wasn't either (if I'm properly weighted), ascending and descending in a controlled fashion I was comfortable with. Mask replacement, I dreaded a little but that's because, in 44f water, taking your mask off isn't a pleasant experience!

(the actual skill wasn't a big deal either). Though if you asked me prior to my AOW class if I was a master some of these, I would have doubted it.
Also, I have plans to take the Rescue diver course when I return home. It's one course that from every person who has taken it, said it's the best course they ever took. Until then, I am just travelling around, getting experience under my weight belt and trying to "master" every skill that may one day save my life in a bad situation.