It is rare that I run across a line where I want it all, so don't buy many precuts. That said, I might choose 2 or 4 out of a line, then fill in with what I have that I think works with it, and will shop for things to add. Collecting fabric in this way is one of my favorite things to do in quilting. I'm one of those that feels that using one line takes a little bit of the creativity out of the process (not to say I haven't done it though - and will likely do it again!)