Thanks both for the help and apologies for being a bit slow but I'm not really sure what others do with their images apart from backing them up somewhere.
At the minute I have about 80GB of images stored on my C drive. I also have the same images on my E drive and the two external drives too. When I've imported the images from the XQD card into Lightroom, done all the PP in both LR and PS I need to do. I then copy them to the E drive and the two back ups. Do I really need to leave any of the images on my C drive at all?
Just so you're aware, the RAW files are never modified when editing in Lightroom. Any edits you make in Lightroom are stored in the Catalog file, not the image itself. This means that if you want a backup of your RAW files, it really doesn't matter whether you back them up before or after you edit them, because they are never changed during the edit process. This is on the understanding that all your edits are stored in the Lightroom catalog file, not the image itself.
Your question "do I really need to leave any of the images on my C drive" has 2 parts to it....the first is whether you need to import images to your C drive at all, and the answer is
no. For improved performance, it is reccomended to import all your images,
and your Lightroom catalog file on a 2nd drive. As long as you specify this file location to Lightroom, everything will work like clockwork (and that is what my link explains how to do).
The second part is whether you need to keep your RAW files in their original import location, and the answer is that it depends whether you want to continue editing them. If you've made your edits and exported as JPG, and you no longer need the underlying RAW files, you can move them to an archive or wherever you like...just be aware that Lightroom will display a ? for any folders it can't locate.
In terms of backups, no you can't have too many backups but 4 copies of the same files stored on the same machine is overkill IMO....you want to put the backups in different locations to see any additional value.