Wow I really didn't mean to take so long to reply; sorry!
I don't think everyone rewrites from scratch, but it can help! It's kind of like writing a different story lots of times because it can change so much from what you wrote before! I think it can depend a lot on how accurate to the story you think your writing already is - lots of times my stories get almost completely unrecognizable when I start over because I had to change so much, so pressing the reset button on those was a good idea! They needed the room to grow! Also that makes sense about feeling like you have to change details; I think f you really like a scene the way it is, you could leave that one out of the restart, or only restart from scratch on scenes you know need help! Although, I also find that sometimes rewriting a scene from scratch can be helpful for getting to know the characters and the story a little better and solidifying your choices in the plot even if you put the scene back to the way it was before! Also if you rewrite from scratch a lot sometimes it's way too boring writing the same scene again and again. I had that problem with scratch-rewrites of my main story where I wanted the first scene to be the same every time! Eventually I scrapped it because I was bored of rewriting it and I'm still not sure that I don't want to go back to that scene (maybe I do! Or one similar to it. It would have to be not so terribly written, though), but it helped a lot anyway!
Looking at other pieces of fiction can be really inspiring, right! If it's done really well you can examine how it's put together and think about how they made it seem really good! Then maybe you can use some elements of that in your story, not necessarily copying, it could just be something like "oh, wow, I didn't realize how much scarier scary scenes are if you give a clue beforehand that the character is scared of things like that..." I write character-based stories, too! Plots aren't that important to me; it's way more interesting to see how the characters react and grow while the plot is happening! If the plot is bad, that makes it hard to have good characters, too, because how can you show the reader what a character is really like if the character is never challenged?
I couldn't stand Tolkien :( I do think there's some value in putting pretty words together, because that's also a form of art, but it's not the same form of art as story-telling, and the two are frequently really dull when mixed! "Wasted" words just make the reader bored and forget what's going on and they skip around and accidentally miss things that you snuck into the lengthy descriptions. And it can go really really overboard; I have a book where it spends several pages (in the beginning, no less! You're supposed to catch the reader's attention...) describing a dress. It wasn't even an important dress, just a tiny background detail. The character's having an internal monologue at the same time, but she's just thinking the same thing over and over and over again. So you could skip the whole first chapter and lose almost nothing. I sometimes have way too much fun describing something, but that's okay, I can edit it later if it turned out too flowery!
It's good to try your best, but that doesn't mean no mistakes ever oh no oh no. It's okay to just enjoy something or to just get something done; and then it turns out better in the end anyway, or at least exists in the end, which can't happen if someone's too afraid of making mistakes. School's kind of different, because making mistakes really can make bad things happen like having to suddenly pay a lot more on tuition becuse you lost your scholarship! But writing is definitely not the same way, and it won't ever be that way; even if you're a professional author getting paid to write, the best thing to do is still get the words out so that you can edit them! With more practice you can learn how to make more accurate drafts of your story the first time around as you learn more about planning out your story and about editing and about story-telling in general, but you'll never even get that practice if you don't just write! It is scary, but I'm glad I'm being a good influence!