Though the amount of time it takes is largely dependent on what USB interface you're using (1.0, 1.1, 2.0, 3.0, 3.1) what kind of device you're using (hard drive, SD card, flash drive, SSD), and how large the files are. Took me about 25 minutes to add roughly 30 games, Wii and GameCube. Some people say it's hard, but it's nowhere near as hard as they make it out to be. There's a far quicker and more reliable method of adding games - and that's manually, by making folders and dropping your games in their correct folders.

The best way to fix Wii Backup Manager not working is by deleting Wii Backup Manager and never looking back.