Not a current applicant, but I did go through this. It depends on how close they are. If you can get several in the same area within a few days of each other, it's easy. If they're in separate regions, it's tougher.
I did two stretches where I had 3 consecutive days. It gets tough because your schedule can be tight if they're in different cities. You go straight from one place to the airport, then straight to the hotel, and then get up first thing in the morning and have to do the same thing the next day or two. Remember that you're going to be travelling in late Nov and through most of Dec. You never know what the weather will do to your travel plans, even on top of the regular airport delays. At one program I interviewed at, we were flying from a city that had a snow storm. I didn't get to my hotel until 2 in the morning, then I had to get up to get ready in time for the 7:30 interview day. You also see where people will have to leave the interview day early to get to the airport on time to get to the next place. This makes your day a lot more stressful.
When I did it, I tried to get as many in on one trip at a time. That's because the closest place I applied to was a 6 hour drive, so I had to fly pretty much everywhere. I did a lot of trips where I went through 3 or 4 cities at a time. Since this was late 2001, and I did a lot of last-minute buying of one way tickets, it made me popular with the security folks, so I had to add an extra hour on to my time at the airport.
Ideally, it's nice to have a day between when you're travelling between cities, but the fact is, it's not always possible to do so.