Best Method to Show Duplications With Increasing Severity

Hi, hope someone can help with this. I need to be able to identify which of our assets are showing up as being repeatedly out of compliance over time. Each week we produce a list of asset names of devices that have not updated in the last 7 days, I then transfer that to a column in Excel sheet (between about 800 and 1700 cells) with the date at the top. Over the course of 4 weeks I would like to show by increasing colour severity (green to red) where each asset is showing up in each column. I used the following conditional formatting formulas for the area of cells that contains data - =COUNTIF($C:$X,XEZ1046847)=2 ; =COUNTIF($C:$X,XEZ1046847)=3 ; =COUNTIF($C:$X,XEZ1046847)=4 ; =COUNTIF($C:$X,XEZ1046847)>4 and applied each of these rules to =$A$2:$F$1733. However nothing is happening, the cells aren't changing colour and I don't know why. Is this formula asking too much of excel (checking every cell against ever other cell continuously)? If so is there another way to do this that is more elegant and less intensive? Thanks in advance.

I think you should try changing XEZ1046847 to XEZ1 in each case.