Every single time there is an update to Witcher 3 the game downloads all 50GB again. Obviously I would prefer this not to happen not only for connection reasons but because of using an SSD. I've already used the "Verify/Repair" option and it continues to occur.

Has anyone else experienced this? Is there some sort of fix?

Turn of auto update in Galaxy.
In Galaxy go to the game page and choose extras. Download the patch.
Or use your browser and login at gog.com and go to your library. Find the game and manually download the necessary patch file(s).
In both cases you will have to manually install the patch by double clicking the executable.

FYI:
4.02 to 4.02 hotfix (1 file) is 8 MB.
4.01 to 4.02 (2 files) is 2.1 GB.

Yup, very annoying indeed. What HetogJan suggests should be how things work when the auto update option is turned on.