Thanks for answering your own question, Javier.
Good modeling tutorials are the ones that explain a tool and then show a wide variety of options with it.
Messing around with the given things is surely a long-term advantage, As it fills your library of options.
I had a head start as one of my first educations was to be a Technical-Draftsman. Which certainly pushed modeling later on in 3D a lot. Some might tell you to brush up on math. It is, in other words, a mixed bag. It's hard to generalize or bottle up in a one-size-fits-all manner. I wish I could!
In my first hands-on classes two decades ago, I asked people to find as many ways to create a cube or a sphere with all the things available. I think since then we have doubled the amount of options.
Another suggestion I love to share (and have placed into a book (not published… yet) is where ever you are, there are things around you; while not on a computer or iPad, what shape is it, how was it produced, and what would help to recreate it.
But to answer your question, what do you like to produce, e.g., what is your main area of interest, work, or industry? That would help me to suggest relevant material.
Keep asking questions (please, in new threads), and I'm happy to share different ways to solve the same problem. In the previous forum, sadly, I am not online anymore. I had at least three ways to do things whenever possible. I try to continue with that if it helps.
Enjoy your weekend