Review several recent games and look for mistakes that repeat. Use the engine to check each position, then choose one pattern to practice.
Look for repeated mistakes
A bad move in one game may be a one-off mistake. Compare it with other games: do you keep leaving pieces undefended, missing the same tactic or reaching positions without a plan? A repeated pattern gives you a clear practice goal.
Step 1: Gather your recent games
Export a batch of recent games from Chess.com or Lichess. Include wins and losses. More games can help you distinguish a repeated mistake from a single slip.
Step 2: Analyze with an engine
Run each game through Stockfish. Note moves where the evaluation worsens, then replay the suggested continuation to see why. Let important or unclear positions analyze longer; a depth number alone does not prove the conclusion.
Step 3: Categorize the mistakes
Group them: opening, tactics, middlegame planning, endgame technique, time. Count how often each category appears.
Step 4: Choose a practice priority
Consider how often each mistake occurs and how much it changes the position. Use that to choose a practice priority. An engine evaluation is not a count of rating points lost.
Step 5: Practice, then check your new games
Practice the pattern in several positions and explain the idea in your own words. Review it on later days, then check new games to see whether the same mistake still occurs.
Doing this automatically
Connect Chess.com or Lichess to let Mainline analyze your games, group repeated mistakes and suggest related practice.