I used to think they're all scams, but I know a few people that got started off with a good course.
There's definitely useful stuff out there, especially about ecomm. I would stay away from the mainstream stuff though ("start an agency", "affiliate marketing").
Interesting post. Why do you think this setup is better than multiple adsets with their own budgets? I'm in a situation similar to your client's initial setup.
Don't you have the issue that out of 3 creatives in the test adset, only 1 is spending? Or you never add 3-4 at once?
Also, do you think this setup would work for Facebook placements only? Btw, you're using no adv+, right?