How to reproduce:
1. Open the attached "SBPCacheValue.7z" Project
2. In Edit>Preferences>SBP set the cache maximum size to be 1GB
3. Run the following command in Command Prompt:

<pathToEditor>/Unity.exe -quit -batchmode -projectPath <pathToProject> -executeMethod SBPCache.SetBuildCacheValueB

4. Check the size of Library>BuilCache folder in the Project directory

Expected Behavior: The Preferences are respected and the size of the Folder is lower or equal 1gb
Actual Behavior: The Size is over 1gb

Reproducible(Unity versions): 2018.4.26f1, 2019.4.5f1, 2020.1.0f1, 2020.2.0a17
Reproducible(Package versions): 1.8.6, 1.9.0

Note: Sometimes you need to wait for a bit to let the method finish