install size Update vs Clean

@Roger
My Win8.1 machine Windows folder is 16.0GB
my Win10/64 machine Windows folder is 12.5GB
my Win10/32 machine is 8.28GB
SO: Your 20GB is no where near usual
and:
Now that you posted the instructions on cleaning it, why don't you post the rest of the instructions on how to determine if it should be cleaned
If I run your command to clean it and there's no change I'll be back with "didn't work!", what do I do now????
just a thought............................

I said ~20GB but actually it is 17.5GB to be exact.
It is very easy to explain. Here's is my desktop Windows10X64 build 10102 with a few applications installed and yes it is 12.3 GB:


Now the question is How many applications software did you install in yours ? Don't forget when you install third party software, majority of DLL's are also put in C:\Windows, C:\Windows\system32.

The screen shot I've shown in previous post are fully functional Windows 10 Build 10074, same desktop, with tons of third party software + MS Office installed:


So The difference between 17.5GB from my previous post and 12.3 GB are from the third party software, not from Windows.

Hope this clears up the confusion !!! :)