How to wind a transformer for multiple output?

[MaXiZ]

As subject.. what's the correct way to wind a transformer to have multiple output? For example...
Input: +12
Output: +/- 15; +/-20

Is correct to wind a secondary for each voltage or is correct to wind a secondary with a "break" at the voltage needed?

 

[Nelson Pass]

Either works fine. Separate windings have the additional
advantage of flexibility, otherwise, they perform the same.