I started out using bondo only. After taking classes from Rick Carter and Bill Yox, I primarily use ear liners because I personally can get a much better ear. However, I still have to break out the bondo once in a while. I was mounting a corsican ram this week and was ready to do the ears. I usually buy things several weeks in advance, sometimes months, so I can order in bulk. Usually I have time to test fit a hide on a form and do all the form prep, but I usually wait to do anything with the ears until the day of. Yesterday I went to do the ears and when I opened the bag of earliners. Both were left earliners, and one was a different size. If I didn't know how to do bondo ears, I would have had to freeze the hide until I could reorder correct ones. Because I can also do bondo ears, I just carried on and it looks great. It always pays to learn how to do things multiple ways.