Of course you are right. And this one of several reasons why I'm flying in C and F (Y only on short hops). I like to keep things civil.

Sounds like a good policy!

I would say that the "maximum duration" is inversely proportional to the number of people waiting to use the lav! In other words, the more people waiting, the less time you have. And I agree with those that posted that waiting until 1 hour before arrival to do this was bad form. If you are going to do the works in the there, it would be thoughtful to try and do it before the "pre-landing rush hour".

I remember waiting in line behind a guy waiting for the bathroom to fix his hair. I politely suggested that if he was just fixing his hair he should wait til I've taken a leak and then he can go for it. He was obliaging, fortunately.

I would suggest if it takes more time that you would to have a crap then wait til you're on the ground.

45 min on Lufthansa!
 

A friend was flying LH on a CAI-FRA-SFO itinerary with an upset stomach. He took some mild all-purpose sedative at the beginning of the FRA-SFO flight, but it knocked him out, unfortunately while he was in the lav. One of the LH flight attendants opened the door and helped him out after about 45 minutes. He was fine once he got back on the ground.

-Hayden