I was in J YVR-YWG last night and after noticing the steady stream of people from Y lined up in the aisle I approached the in charge and asked a) why there was no announcement for Y to use the Y lav and b) why not close the curtain between cabins.
Turns out the Y lav was out of service and only the J washroom was in use. I can tell you it was not a pleasant experience to have people standing all around me and when I went to use the lav it was a real mess.
I understand the need in this case to use the J lav and have no issue with it I just wish they had asked people to line up in Y and not J.