It used to be commonplace, but at this point in the NFL, there aren’t a lot of teams that actually go away and travel for training camp at an off-site location any longer. There are teams who use facilities other than their own, but they are nearby and players are not asked to house themselves there during that time.
The Pittsburgh Steelers are one of the few who do, and their consistent tenure at Saint Vincent College in Latrobe is unsurprisingly the second-longest arrangement between any team and any one site currently active, behind only the Green Bay Packers, who have held their training camp at Saint Norbert College since 1958.