Most of my work travel is with short notice, usually 3-5 days. It's rare that I catch something so critical that I (or others on my team) have to be there, on site, in fewer than 24 hours. I'd say that's happened only a handful of times in the past 10 years. Usually our clients understand that the best way to troubleshoot an urgent problem is to collaborate remotely for the first 24-48 hours and schedule onsite travel with, say, a 2 day lead time so it's less costly, not to mention more feasible to rearrange people's schedules to get out there.