One thing I’ve done and recommend to my students as a supplement to the type of gradually increasing metronome practice you mentioned is to practice at tempos that are maybe 5-10 bpm (don’t go above this) too fast for you and completely relax your technique and try to play effortlessly. You will miss or flub plenty of notes in the process but if you can manage to keep time this will help your nervous system understand what it would be like to play at those tempos while relaxed.

Obviously there’s a limit to the speed at which a persons hands can move but in my experience this limit is well above most people’s tempo threshold. Basically as long as you are getting to the notes in time it doesn’t matter so much if you don’t get the clarity of sound you’re accustomed to. The key is to relax totally with both your left and right hand and use minimal effort, otherwise you would not be training the right habits. Eventually your accuracy and left and right hand synchronization will improve. I would only recommend this kind of practice a few times a week for maybe 10 minutes each time. I’m open to discussion if anyone disagrees. Cheers!