Changes

As a comparison think of it as a leaky bucket. The holes are the cool down mechanism but every time you cast you dump a load of water in. The more favour you used, the more water goes in. With the bucket you can only cast if the bucket is less than three quarters full. Space your casts apart enough and the bucket is always almost empty. Cram the casts together and the water cannot drain off fast enough. Get a big cast as your last one and you can pretty much fill the bucket to the brim which means you'll be waiting a while to cast again as it has to drop to only three quarters full.