One can debate the title/comp level where this change happens but, certainly, at some executive level it's reasonable to expect to be contacted off-hours if there's some customer/PR/facility/etc. crisis. That's not to say an exec can never be out of touch; a friend told me that their former CEO had a new communications head quit because they couldn't deal with said CEO telling them that they should just deal with PR issues if he was on vacation.But, above a certain level, traveling on the weekend, being away nights, late night calls, and yes the occasional "Houston, we have a problem" moment happen.