Is there a way (or a third-party app) that show which files and folders we access the most?
I would like to know that so I could have an idea which files are really important to backup more often and maybe move them to a separate folder to avoid having the backup to scan 1TB of data when maybe I just need to backup 1GB of files I use more often.
MacBook Pro 13″
Perhaps. Please review Optimize storage space on your Mac - Apple Support. Its Reduce Clutter option will identify seldom used apps and files for you to review. Choose "Show in Finder" to navigate directly to them so that you can decide whether to delete them, or move them elsewhere.
Although you did not ask, bear in mind that Time Machine will only back up an item once, unless of course a change is made to that item. You can also exclude specific items from being backed up: Exclude files from a Time Machine backup on Mac - Apple Support. If you choose to move all those items to a separate folder and exclude it, that might also be a solution to consider. Although that document's title implies you can only exclude files, you can exclude entire folders or even connected devices such as hard disk drives or flash drives. A more accurate title would be "Exclude items from a Time Machine backup".
Find which files and folders are most used/accessed?
