It's kind of in the middle;-) As Rolf says if there is other code that takes all the CPU then sure, the wait included in another code does not help...But for the code that the wait is involved in it will allways ensure a halt, contrary to the wait until next ms which would immediately let everything run if the target ms has been reached already.
If you could post a picture of the code or the code itself I'm sure we can find a solution/explanation.
