The 767-300 or ER category is a different beast because the category has both domestic and international flying and involves both the 757 and 767. The Intl goes much more senior. I'm guessing someone hired in 2007-2008 or maybe a 2010 could get weekends off in that category if they fly domestic.

As far as a pure intl category ala the 767-400, A330 and 777, it depends on reserve or lineholder. Reserve goes very senior on these airplanes and to hold weekends off on res would require at least 16 years. The good thing about 6 and 7 day trips is that if you do 2 a month, you automatically get a couple weekends off too. As a junior guy on the 767-400 I can get 2 weekends off a month if I bid a line and I'm a 2001 hire.