Unclear documentation for autoboosting with decay

Hello

I'm have a hard time understanding and using autoboosting with decay.

The customer wants newer pages to generally be more relevant.

The documentation is quite unclear in my opinion:

http://world.episerver.com/documentation/Items/Developers-Guide/EPiServer-Find/12/DotNET-Client-API/Searching/auto-boosting/

The example in the beginning uses TimeSpan.FromDays(14) as decayScale

Then the tables explaning the effect mentions "20" as a value for decayScale. 20 what? Days?

Then in the spreadsheet example that is linked where you can test the effect scale has a value of 0,1.

I have tried setting different values in my code (that looks pretty much like the first example in the documentation), but I can't se any effect no matter what I set decayScale to...

Hope someone can help, and please make the documentation more clear.