Scales give good basis and strong sense of shape at the keyboard which is helpful when dealing with the key signature. Unfortunately it is not all encompassing in terms of fingering technique and decision making which must be expericed through many pieces. Bachs WTC is a good "Old Testament" to keyboard fingering where Chopin études like the New Testament. Studying countless small pieces will also help reading skills. Scales also do not train thoroughly coordination, harmony, rhythm etc etc.