True, it's people like your jerkish boss or annoying teacher who say things like "The Devil's in the Details." But, damn it, they're right. Detailing is good. And, it holds true in BJJ too.
Jiu Jitsu can easily be done, day in and out, sloppily and without proper care and caution. We're all guilty of poor form in practice and drilling. And, we get away with it a lot, because we're not always called on it (although, I'm sure your coach keeps you in line as best he/she can). That's why learning proper form and then learning to perfect in even greater detail is truly a never ending task.
This lesson reminds of the story of that one really old Japanese sushi chef, Jiro (they made a movie about him), who's spent his entire life honing his simple yet perfect sushi making skills to an exacting, almost unheard of, standard. We all need to do that with our Jiu Jitsu practice.
So, go practice making sushi or something. Here's a video of Clark Gracie (alongside Stephan Kesting) demonstrating the finer facets of his rear naked choked method.