I think you're doing your due diligence, and that's a good thing. But you'll achieve ultimate success with your tub once you sever your reliance on, or curiosity about, any other source of advice. No mixing and matching advice. Ignore pool stores, pool guys, neighbors, etc. Give TFPC an unbiased, unaltered, uninfluenced try, and you'll never look back.
The advice you get here, especially from those with a "Mod" or "TFP Expert" designation, is designed, presented and curated to be very consistent. There are a lot of folks giving advice here, but it's all one voice, one concept, one method, based on actual science and torture tested across 1000s and 1000s of pools and spas, over years and years. It is not anything like the collection of myths and anecdotes and dis-proved practices that is picked up by summer employees of pool stores, who have spent upwards of 30 minutes watching the company training video before they take their place behind the counter. A video focused on sales and profit, not science and proper water care (OK, I made most of that up, but it's probably something very much like that!)
Stick with TFP. Go into the pool store for the chlorine and the MA, it's good to support them when you can, you never know when you might need a part that they carry. We don't want them to go away. I even let them test my water once in a while, because they'll send me coupons and discounts via email. I just toss the results paper. Thank you very much. But other than that, you turn a deaf ear, and just nod your head, and give them whatever line you feel most comfortable with "Thanks, I'll give that a try next time." or "OK, let me check with the boss first. He/she runs the pool, I just run the errands!" or simply "No thank you." After a few visits they'll recognize you and leave you alone. That's how it works for me, anyway...
You're doing great here so far, keep it goin'!