What are some typical mistakes in 1700 rated games on Lichess, and what ways are there to correct them? I usually play blitz and bullet games. Occasionally I play. OVB and longer formats.
Even at 1700, the vast majority of your mistakes are going to be tactical errors...especially at the faster controls. The only way around that is to start studying and practicing.
There may be some people, who can benefit from online tactics, but am of the belief that they lend themselves toward the trainee being shallow, and often the answers are the computer answer, not the human answer.
I am a firm believer in books, so get yourself some good tactic books that are well-categorized. It is better to study specific categories at one time, pins, skewers, etc. I still love the Fred Reinfeld 1001 books.
Try to do 50 per day, spending no more than two minutes per problem. Note in pencil on a scale from 1-5 how easy you found the problem because you will do them again in the future. The more time you spend on tactics, the less you will lose online.
One last thing, and that is I have found that even mid-level players think they are pretty good at tactics, but it is my experience that they are not. I am no longer above 2200 USCF, but even when I was, I always felt I could be stronger at that, and general calculating.
I recommend Dan Heisman's "The World's Most Instructive Amateur Game Book" which has 30 amateur heavily annotated games grouped by useful sections like "Too Fast" and "Too Slow" for time management. If you are often mystified by GM commentary like "...and Black is clearly better." then this book may be for you.
Most of these are in the 1400 - 1800 range.
Some quotes from the introduction:
Many amateur tournament players are superior to the average chess book purchaser
Typical mid-level tournament players often play strategically interesting games