I agree. Following the format probably makes it easier to read (since they like to drill the format into everyone's head and profs are used to reading it that way), but I think that as long as you hit all of the major areas, you've pretty much covered what is needed. However, I have had several profs that don't care one way or the other whether you actually use the format. Many of them are just interested in making sure you understand the material and can apply it. I think it is safer to stick to IRAC (no reason to piss off a prof if you don't need to), but you mainly just need to make sure you have addressed everything that you need to. I'm so used to it by now that it just feels easier to do it that way.