Chess positional sketch is one of the great chess secrets especially taught by the Russian school.
Not only does it allow you to improve quickly but also assess your rating improvement.
The idea is that whenever you come across a game or a position that interests you and seems instructive, you make a sketch of that in a notebook. Nowadays, you can do that electronically on any chess app.
Now when you write down the position and what is interesting about it, you revisit it in a couple of months, if it still intrigues you then your level hasn't changed much, however if it no more interests you then your level has definitely changed and increased.
Usually within every 100 position, only 5 should peek your interest.
Look up Artur Yusupov and Mark Dovertsky for more details.
Good luck!
What is Positional Sketch in Chess ? I've seen it in many chess books. They give advice to draw a Positional Sketch to better understand and remember the position. Can somebody describe it for beginners.