To Sub or not to Sub...?

Is it the case that some sub owners tailor their setup to leave a hole or depression at a problematic room resonance frequency? Say you've got a monitor that goes down to about 45 -50 Hz, and you've got a room resonance at about 40 hz. Do you dial out the sub below 40 to avoid that frequency? Does that create any audible anomaly? Or, maybe that's a bad example; is this strategy frequency dependent... e.g., works if the hole is closer to 30 than 40? Thanks.

thanx, Doug, I wasn't thinking of this as a general, primary strategy for setting up a sub. However, I was thinking that many minimonitor users might have rooms large enough that their speakers would not excite the fundamental (if that's the right word) resonance frequency of their rooms, and that going full-range might introduce this new problem. Equalizers and room treatment aside, what I was actually thinking was that I had read mentions or recommendations about people dialing in subs so that their sub and main speakers bracket the problem resonance frequency. I think REL may suggest this. So, I was wondering if any Agon'ers had set up with this as a factor, how the discontinuity between sub and mains affected integration of sound, etc.