Well the covers are never really tight so they blow around. Typically they will rub in the roof membrane enough to cause problems. In some cases rubbing a hole through the membrane. There are other discussions about this on the forum if you search for them.
We used to live north of Columbus, Ohio and used a cover for a couple of years. Trying to get the cover good and tight was a challenge and we even used bungee cords to help. But for the 3 years we used the cover, every spring I had to take it to the Amish canvass shop and have repairs made.