More to the point of this post if you have the time and money then go take the class you will learn allot if you are not the person that has been on the water your whole life.
I have been on the water and travel all over the world as a ships engineer and probably could have got what I call my "little" masters license on my own but I had the time and took the NE Maritme class. I did try to correct a couple incorrect items that they were teaching that were to navy standards and not the merchant marine.....I doubt they changed there teaching but I knew they were wrong
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Could I do 10 chart plots right now, no not really. Maybe half of them. Allot of the test qustions really don't apply to little boats but that is the way the CG tests people. i.e. no one will see and all purpose fire nozzle on a boat under 100 tons, but you may see this question.
It is also a good way to meet more people that you may see on the water.
So I'd go take a class. Most people don't put in enough time on the water to qualify for a license so they exagerate, 365 days in the last 5 years is allot for most people.
Another point is that eventually everyone will most likly need some sort of licence to operate a boat from the state and I would speculate that if you have a USCG license already it would superceed and you would not need to go to a class to get one of these future state operator permits.