So long as you did your best with those 21.75 boxes there's nothing to regret and no reason to be hard on yourself. This course asks you to perform to the best of your ability with every line you put down -- that's asking a lot, but what it isn't asking for is perfection. When I was doing lesson 4, there was a time about halfway through drawing each bug when I felt like scrapping it and starting over, but I fought the urge every time and finished the bug and I am very glad that I did. It's best to build a habit of finishing, not restarting. In later lessons, you will inevitably make more mistakes, and those mistakes will be opportunities to learn how to course correct and make the most of what you have on the page. I think that's more valuable than restarting every time you put down the wrong line.

If you suspect you aren't following the instructions properly you should share your work here or in the discord to get guidance. Definitely don't start over. Restarting does nothing but make you feel more burnt out.

In the end what does the number you write beside the box matter? It isn't like 250 is some magic number that will let you master boxes. Just try to identify something specific you can do better in the next box and do you best to apply it. Boxes should be a regular part of your warmups pretty much forever onward after the challenge, anyway.

Drawing, or any creative endeavor really, is a battle first fought in the mind. Our neuroses - doubts, insecurities, impatience, perfectionism, frustration, reluctance, etc are all the demons we all fight in that battle. The more we give into them the stronger they seem to become. To the best of your abilities, don't.