Well, in my case, it is just the opposite. My time is valuable, but the time of my clients is even more valuable. Since my work normally involves day-long meetings of 10 or more people, there is no way that I can say that my time is more valuable than all of theirs put together (not to mention trying to reschedule a full free day for multiple people). Given that my travel times are normally in excess of 10 hours, and often in excess of 15, with multiple flights, I always build in at least a day of slack on my way out. . .and it isn't like I can't work at my destination. This also allows me to get a sense of the city/country that I am going to which is important in my work.