Hello Yaroslav,

thanks for the speedy reply and your question.

There are different schools of thinking. Most important would be the "rule" of keeping the changeset local. No need to upload each change individually but try to keep it city-sized.
You're free to keep each changeset focused on one topic or just walk down one street and fix up everything you see. Just write a comment that makes people understand what you did and why. That's all.

Please reach out if you have any more questions. Always happy to help :)

There's also a rather expansive wiki at wiki.osm.org and a community (forum) at c.osm.org which can be asked for help 24/7

