People that can learn on their own by going to just group classes are probably very talented, or have some background in dance (ballet, ballroom). I know a lot of people that go to just many group classes with different instructors, and I haven't noticed that they have progressed very much. I am talking about at least 2 group classes and 2 practicas per week. Like no difference within 6 months time period that I observed; they seem to be stuck. I also don't believe that dancing more at practicas would help them, since simply there is no enough attention in group classes to tell them exactly what they need to improve. So, they keep doing the same things over and over (incorrectly)
I think private classes take time. I've been doing them for 6 months weekly (1 per week) in combination with group classes, practicas, milongas, and the progress has been great. I do 2 group classes, 1 private, 2 practicas, 1 milonga per week, and 15 minutes per day at home just by myself. I would do more, but my legs are just sore lol. I feel that I need to come to practicas and milongas fresh, to really give it 100% to the follower. Otherwise, If I am tired, it is all becoming robotic or I make more mistakes.
Which kind of brings another question. When do you stop going to group classes? Is it 2-3 year mark? I find that my group classes are becoming the same. Combinations seem to start repeating themselves.
I use group classes for learning combinations. I polish/clean them at my private classes.
I used to struggle with learning combinations at my intermediate/advanced group classes 6 months ago. Now I seem to get them quickly, but they seem to start repeating themselves. I start feeling that I don't learn much anymore at group classes.