Yeah, it saves you money...by costing the prospective employee. There's only so much we as employees can or should be willing to give up for free, and it's 3 interviews.
I also question if more than that is really improving the quality of your hires. Far more often (100% of the time, in my experience), multiple interviews are more a symptom of bureaucracy; multiple managers insisting that they get to stick their fingers in the pie, rather than actually learning anything more meaningful about the candidate.