I started with Bob Sparks, who the grounds at Treasure State are named after. He would have been a legend in the sport had he not passed away much too soon. What he taught me & others was enough to get us going & be able to recognize when someone was not doing things right & why. We also had "Training Your Retriever" by James Lamb Free (the Richard Wolters of the FT sport). Get a copy & read it sometime, you will recognize the growth of training methods, pretty antiquated in those days.
After having been around awhile I trained with Mike Greene for about 4 years when we had similar dogs - after work training dictates that you have to limit your setups, hence similar dogs. Also trained through one dog with a pro & learned a lot of do's & don'ts.
A beginner has to recognize they need to have a cursory knowledge of what's going on to benefit from some training situations. Going from Grade School to attempting your PHD just doesn't work, too much gets missed along the way.
One of the things where experience is a benefit is an ability to recognize when someone is doing something right & being able to ask them how they got there. It is also a great reminder that all dogs are not alike & need to be brought along with different methods. All the good Amateur trainers have a fairly constant pattern they follow regarding introduction to new situations. & there are many of them, situations & Amateur trainers.