When I bought my latest machine, it came with “classes.” I learned a bit, but to me it seemed like little more than a sales pitch. “Don’t use thread, needles, bobbins, fabric from anywhere but our store. If you do, it will ruin your machine.” Personally, I use whatever I like. I use lots of C&C and connecting threads. Lots of people love the high dollar threads. To each their own. Use what you like and don’t stress about what anyone else uses.