I did everything in the core learning system. I started with the fundementals even if I had been playing for a couple of years (self thaught). I learned a lot in the fundementals. I suggest you do them too. It will fill the gaps and hole.

The best way to learn is slowly. Trying to go to quick will only make you forget what you learned (i know from experience). A strong fundation will make you a better player and you will learn more easely.

The blues curriculum is to my opinion the strongest element here on guitar tricks. Again, starting with level 1 (even if its easy at first) will help to fill the gaps and hole. The blues curriculum helped me a lot with my improvisation, thanks to the incredible videos that Anders made on how to improvise and build your own licks.

I think that the country and the rock sessions are good but not as strong as the blues one.

Take your time and have fun :)