There is always a risk to letting some element of style become a crutch. It's pretty normal to go back to things you've had success with, but when you do so without questioning why and find that you have done one thing when something else may have been a better choice, then there is a problem. But, if you can see that has happened, then you can try something else next time.
As someone who shoots formats from 35mm to 8x10 and also likes to use some shallow DOF at times with all formats, I can say with certainty that David and J Brunner are right, LF rules for shallow DOF, even without movements. That's why folks are using speed lenses on Graflex SLRs and Aero ektars are hot lenses for graphics. If the formula doesn't fit that, then the formula is missing something.