Someone has to occupy the 500-700 elo

You should see improvement in that time. If you're stagnant/regressing over the course of 4 months/1500+ games, it's time to do some introspection/review to see what's going on with your chess and your approach. Don't give up, but also don't keep making the same mistakes and hoping for a different outcome. I promise it is 100% possible to do so, you just need to change your approach.

Learn and apply the most important principles of chess. - (core of my teaching)
Always blunder-check your moves.
Solve tactics in the right way.
Analyze your games.
Study games of strong players.
Learn how to be more psychologically resilient.
Work on your time management skills.
Get a coach if you can.