This usually happens because you do not use the proper resolution. A good tip is, before you begin to compose, calculate that musical figure is the smallest that you are going to place, so that a line is equal or inferior to that figure. Thus you determine the resolution.
In the opposite case, if the song is already composed and you are in the nuances phase you can use a Dblue tool to redistribute the patterns in higher resolution tracks. That is, you can duplicate the number of lines easily: