A lot of good tips for beginning writers. When I was a young artist I heard this advice, which dovetails with one of your points: “It takes a thousand bad drawings to do a good drawing.” What they meant was, you learn something with each drawing till you master the craft and know what you are doing. I think that applies to your 52 stories point.
I would add here that you should study the masters of the craft simultaneously. Chekov, Hemingway, Fitzgerald, London, Borges…. Sometime even imitation will teach you things. Modernize a 100 year old story, for example. See how the story was structured etc.
I might quibble with one point… having stories take place in one setting. There is a danger that a young writer will produce “scenes” and not stories. That’s maybe a blog post of my own.