Scan progress bar vrs x% progress

When I do a manual scan of my system, which I do daily, the progress bar works fine, but the percentage of progress looks like it doesn't know what to do. I end up with a / \ / \ (rotating slash) and periodically a number will show, but it is usually 0% or maybe 60% (which reverts back to 0%). I thought that it was reflecting the % of each file that it is scanning at any particular moment during the scan. Does everyone else experience the % of scan working this way?

 

If I remember correctly, the percent-value is displayed when it's processing archives.

Best regards,
Anders