Not anymore. NANPA's standard policy is now to overlay all area codes needing relief. I'd guess the reasons would be that most people are used to 10-digit dialing, which wouldn't be prevented very often by passing through three area codes from downtown to the suburbs anyway, and businesses complaining about constantly having to change their advertisements and business cards.
I remember when all the Houston and Austin radio stations had their request/contest lines starting with "390." "Call 390-5-K98!" "Requests and dedications all night long on Majic 95.5 KKMJ. If there's anything I can play for you, call 390-KKMJ."
San Antonio was "470," and DFW was "787," though I think Dallas might've had a couple of 263's. From what I was always told from my time working for the phone company, that was to make sure, if any circuits got blown during a contest, it would only be the radio stations' circuit so everyone else could otherwise make emergency calls. Not sure how well that worked in the real world, though, as I can remember hearing a person or two died in Dallas in the early 90's when they couldn't get through to 911 because too many people were trying to call in and buy Garth Brooks concert tickets. Also seems like the entire system in Amarillo blew when KGNC 97.9 had a contest the first week of summer break, though I don't know if Amarillo had a single circuit for radio stations at the time. I suspect that's not the problem it once was now that most people aren't on the public switching network.