If you’ve got a couple of VMs, then trimming them occasionally will help with storage management on the host. Disk files (like VDI and VMDK images) will grow over time if the VM was configured to expand the disk as needed – but they will never shrink on their own.
This was tested on a Windows 10 VM managed by VirtualBox, the starting file size was over 40GB, as it had been used for various roles and grown over time.
