I would guess most of your exposure to business travel is within tech or consulting, which rarely require last-minute booking. I would imagine most last-minute bookings for business travel come from people in sales. I’ve seen many sales people find out a prospective client is open to meet and immediately hop on a flight just to potentially make a sale. The opportunity cost is worth it even for small businesses. My exposure to this was for wholesale and retail distribution of consumer electronics but I’d imagine that this would apply to any business with a sales team.
About half of the work trips I've been on, the tickets were booked at most a couple days in advance. The most expensive ticket I've ever bought was an economy United cross country flight to LAX for $1500 (booked about 14 hours in advance) and I've done a lot of vacations to Europe. We booked it last minute because we didn't know when the project would be ready to deliver and once it was, we had to deliver ASAP. I was on the ground in LA for about 12 hours before flying home. Awful trip. Largest ratio of dollars spent to enjoyment received I've ever experienced.
