Okay, so all take in mind, you are doing good on your exercises up to this point, though what more of what you are missing is on of the more important things about this course, which is not working alone and relying on other people to give you feedback, so you can grow and develop faster.

I would suggest you just do exercises from lesson 1 and 2 for wamups, this consists on choosing one exercise that you wanna work on, it may be related with what you are working (organic arrows if you are doing plants for example) and do just 15-20 minutes of it, maybe a page, not much. I don't think you need to go back and do them after you are done with lesson 4, just try to incorporate them in your warm ups.

After you are done with lesson 4, try getting it critiqued on the #critique-exchange channel on the discord server, you need to stop working on a vacuum, the idea of this course is to get help from others in real time, you will see how it changes the game completely!

So, keep going wtih lesson 4 and then don't move until you get it critiqued, which you can get it, on the discord server! Good luck.