steep roofs usually leak far less than normal slopes because of the water running down much faster and gravity action.
However if you have leaks, first check where stuff was added to the roof that required making a hole. Skylights are notorious for leaking, fireplaces on steep roofs usually need crickets built to divert the water away from the chimney structure.
Leaks can be detected over time from the inside of the attic looking at rafters and finding stained water trails. Follow them upward and there usually will be the origin. But it quite a process.