It would appear as if Copywhiz is copying all files on Windows. But in reality, it would skip files that are not required to be copied.
When you paste new or modified files, Copywhiz does not copy old files. However, this does not mean that the old files will be deleted from the destination folder. This functionality only means that same files will not be copied again. This way, you will save a lot of time.
The new update also displays how many files were actually skipped. You can download and install new update from here: http://www.conceptworld.com/Copywhiz/Download
If you want to pick files created & modified after specific date then choose the 'Paste files by date" option inside a new folder. With this feature, you can be sure that older files are skipped completely.
Watch this short video for clarity: