> Probably almost any method is effective at learning guitar, as long as it includes the key factor - time spent practicing.

There are a few pedagogical points here to keep in mind:

first, there are local maxima in terms of learning something like guitar where you get bad habits and the only way to progress is to undo them.

Also, different ways of learning have different values in terms of what goals you're aiming towards and very importantly what kind of practice will keep you motivated in a sustainable way. Sometimes, taking shortcuts in some ways means you might slow down your growth rate but you'll have better overall growth because you'll keep at it for longer