It is certainly more loosely enforced than GS or Flagship First check-in, because any enforcement that can be done is typically done once the passenger is already at the counter, unlike the other two where the passenger needs to deal with a "bouncer" to "get in line," i.e., to get into the check-in lobby/room. Personally I only really care about this enforcement, or lack thereof, when there is a sizeable line of actual 1K/Polaris passengers, such as during the international banks at SFO.