NIS 2012 Scan Performance Profile setting inconsistent

By default the scan performance profile setting in NIS 2012 is set to standard trust.

With that setting it is supposed to skip Norton and user trusted files.

I found that the number of skipped files to be grossly inconsistent using that setting.

 

I am using the standard trust setting and sometimes the scan takes 47 minutes with 392,480 files,

and other times it takes 9 minutes with 167,782 files.

 

The big difference occurs in the files and directories category.

One result shows 384,550 files scanned (162 skipped) while another scan shows 159,782 files scanned (136,968 skipped).

384,550 minus 159,782 = 224,768, so the amount of skipped doesn't jive either.

 

I have a PC counted 200,608 files on 2 drives (3 partitions).

I have 63,276 files included in a scan exclusion setting on one drive.

The number of trusted files is shown as being in the 3,900 files area. 

 

All of the other scan categories are fairly consistent in the number of files scanned.

 

Why do the Norton (or user) trusted files vary so wildly from weekly or back to back scans?