Trying to understand the options

Linux Mint 18.3 Cinnamon 64 bit TS 17.11

In the schedule I have selected to run once a day. In the Scheduled tab that option is starred and apparently that indicates that the scheduled task runs ever hour. I do not understand what runs every hour. Only one snapshot is created per day as per the schedule I have selected so what happens every hour. The only thing I can see is that it mounts the destination HDD (an separate internal one in my case). Why does it do this and why, once the task, whatever it is, has completed does it not unmount the destination drive?