Personally I took my diagnostic and began with the LSAT Trainer. While it helped, it didn't teach me the fundamentals. The Loophole (my favorite book) is something I recommend if you struggle with the fundamentals/need extra support. Its a good book to have.

Your score increase will definitely depend on how well you understand the questions and tasks given! I haven't used 7sage for the curriculum but I think you should follow the advice above before anything. You've paid for a resource and should use it to the fullest extend. I would recommend doing drills and seeing how well you comprehend the content.

I do a lot of drilling and practice with people on Em's LSAT Study Group on discord!

If you want a community I recommend it since its free resources and a positive community! https://discord.gg/amsTBhPS

Instead of understanding why it was wrong/correct try reviewing it in a way that will have you reevaluate how you approached the question and went down the wrong path. You'll find that a lot of this is habitual. A simple "how did I get here?" will help a long way. Putting a pin on where you are going wrong will help you narrow down where the adjustments are needed. The Loophole (my favorite book) suggests having a wrong answer journal that does just that! Write the question, stimulus type, how you got to the wrong answer, and how you might fix that approach. Hope this is helpful!

I help run a free study group on discord where I help adjust people's approach to questions. If your interested in that you can shoot me a message!