Hi,
In the forty+ years I've been quilting I have done it all. For my best work I make my own binding. For items like Linus quilts I usually do the pillowcase method and create a mock binding by stitching around the outside edge to create the impression of a binding. I use commercial binding when I want something unusual like gold lame'. I also use commercial binding on craft projects like purses etc. There is no right or wrong way. Do whatever suits the project and you.