Hmm I had a similar experience but with different results. I took fairly hard but common problems that I had to do and started timing myself.
First time it would be like 2 hours, then I'd get it down to 1.25 hours. Then 45 mins. Then finally I got it down to 18 minutes and couldn't get it any faster. I learned so many tricks and it really burned into my brain all the different faster ways of doing things.
I noticed at work I got way, way faster. I ended up outperforming my entire team, by myself. I think mostly because A) I now had a habit of working fast B) I viewed it as a competition, so no water cooler talking C) I didn't have to think about how to do it, I just knew, and I knew how to do it quickly.
It literally took me from making 75k to 400k in 2 years. I just applied that to everything I could, so when doing interviews I was able to just flood the interviewer with the depth of my knowledge and how fast I worked.
Now I really put in a tremendous effort into this, not just a few hours, it was an obsession for me. But once I did it I got those skills for life. Even now that I'm rusty I still go really fast.
Also, my code quality itself is quite good, because I'll write it as fast as I can (frequently only takes 15 mins), then refactor like crazy (5 to 10 mins) and still be an hour faster than everyone else.
First time it would be like 2 hours, then I'd get it down to 1.25 hours. Then 45 mins. Then finally I got it down to 18 minutes and couldn't get it any faster. I learned so many tricks and it really burned into my brain all the different faster ways of doing things.
I noticed at work I got way, way faster. I ended up outperforming my entire team, by myself. I think mostly because A) I now had a habit of working fast B) I viewed it as a competition, so no water cooler talking C) I didn't have to think about how to do it, I just knew, and I knew how to do it quickly.
It literally took me from making 75k to 400k in 2 years. I just applied that to everything I could, so when doing interviews I was able to just flood the interviewer with the depth of my knowledge and how fast I worked.
Now I really put in a tremendous effort into this, not just a few hours, it was an obsession for me. But once I did it I got those skills for life. Even now that I'm rusty I still go really fast.
Also, my code quality itself is quite good, because I'll write it as fast as I can (frequently only takes 15 mins), then refactor like crazy (5 to 10 mins) and still be an hour faster than everyone else.