Any good trainer will equip you with the basics in 2-3 sessions but if you are enjoying the classes and Ernie is responding well then, personally, I'd continue until I had some confidence I knew how to react in different situations
Pearl has very little chase instinct and no retrieve what so ever ! We had 3 lessons in total and find working her while walking is much easier! The trainer did say that cockers shouldn't need great long walks just 20-30 minutes of being worked (quartering, recall, stop on whistle etc) would be enough. All dogs are different and I was brought up with gun dogs do know the basic commands - it has been a lot of fun working her though and she clearly loves turning on a pip
My best advice on finding a trainer is to speak to them before going for the first time. You should hear phrases such as "hands on reward only" which means no gravy bones
but also giving attention is the reward - make it clear that you don't support any negative punishment, although this is now archaic in gun dog training as dogs are far more sensitive due to breeding. Sadly I'm sure there are still some trainers who use bullying methods - maybe go along to watch a session before taking Ernie?