According to two VW manuals I have, the correct amount of brake peddle play is from 5 to 7 mm. This is critical. If you have NO peddle play at all, the master cylinder can not return to the state of taking in more fluid from the reservoir.
To check the initial peddle play, press the peddle with your little finger ONLY, Not your foot. With very light pressure you can feel a point of resistance. Measure this movement with a metric rule. 5 to 7 mm is it. No more and no less.