how many days I get off :).

12 weeks summer (sometimes 11.5 - depends on when days fall - nbd)
2 weeks christmas
1 week spring break (there's your 15 week magical number)
1 week + 1 day for Thanksgiving and Fall Break (Now we've hit 4 months)
Labor Day, MLK, Presidents Day = 17 weeks

Plus 2 additional paid weeks off. That's 19 weeks right there.

Now the efficiency thing - I will say this. Many of my colleagues and friends who teach are absolutely pitiful when it comes to time management and efficiency. They are great people and great teachers but are gluttons for punishment. There are so many better ways to do things but they are unwilling to budge, change, or adapt with all of the new technologies that make grading and teaching and organizing a breeze. It's not like I'm teaching some cushy subject either - it comes down to the decisions you make and the battles you want to fight. The only things I actually have to hand grade myself all year now are projects that I grade as they present or free response tests that I can work on grading before/after school before I go home. On those I have 1, maybe 2 questions that require hand grading so I'm able to breeze through those pretty quickly.