i dont even look to see if one was done unless the patients history is bad enough to suggest acute intraop problems. I dont think a CXR alone (without associated Hx) would alter how I conduct an anesthetic.
I most frequent time i request them is in the outpt setting where the patient comes in with a hx of new or worsening SOB, or recent cold symptoms with wheezing, rhonchi or crackles in PE