Leaving Verify switched on costs time because DiskSnap reads data back. That extra read answers a useful question: does the saved result match what was intended?
When you back up
DiskSnap reads the completed .dsnap file and checks its stored contents and whole-drive fingerprint. It does not read the source drive a second time. A successful result means the saved backup passes those integrity checks.
When you restore or clone
Verification reads the target back and compares the written data with the expected data. If verification fails, keep the source or original backup. Do not treat the target as a reliable replacement.
When you make bootable media
For raw images, verification checks the written image data. Windows installer media uses file checks. Neither result proves a particular computer will boot: firmware settings and the image's compatibility still matter.
A second copy still matters
A verified backup can still be lost if its storage fails later. Keep another copy of important backups and test restoring to spare media before you depend on them.