So often coordination issues are caused by the left-hand finger placing the note slightly late also making the sound unclear. If this happens, both hands become hesitant and do not commit to the task in hand. Hesitant actions as we know are often inaccurate and can also be quite tight.
The exercise here tests the readiness of our left hand. The task is not to play the first note until the second note is prepared, either down in position (with the correct hand position, finger angle and pressure) or hovering above the note it will play.
If we watch slow-motion video of great players such as Itzak Perlman or Hilary Hahn we see how calm their left-hand movements are, even at high speed. The demonstration here shows how using practice breaks allows us time to program ahead and gives fingers the time they need to get ready and be calm before the bow moves.
It takes time to practice note ahead and often the real work is in your brain!
Practice will be very effective when you program correctly. Take the time to analyse the upcoming task, give the command for the fingers to move and observe whether it worked satisfactorily before either repeating the task or moving onto the next one.
Often good slow practice is really practice with many breaks to give us time for the brain to think ahead.