This varies significantly depending on many factors.
1) What specialty? If competative, you'll have to apply to many programs, and also possibly travel to many programs.
2) Community or academic? Generally speaking, academic programs are more spred out, necessitating farther travel (not the case in big cities).
3) Are you looking to stay in your geographic region?
Some people going into FP apply to 5 places within driving range; many FP programs will put you up in a hotel. The average ortho app seems to be applying to 40+ programs all over the country, and going to as many interviews as can be squeezed into the schedule. It really depends...