I received an announcement about this program yesterday, because I purchased three Roundabout shows that happened to be running at the same time, when I traveled to NYC for a theatre weekend. Buying in this manner saved money and, I think, provided better seating for those shows.
Also, the Center Theatre Group, in Los Angeles, runs a similar deal for a minimum of four shows across all three of their venues. I took advantage of it last season and was not going to do so again until the pre-Broadway revival of “1776” was added. So, this season I have “On Beckett” (Bill Irwin), “What the Constitution Means to Me” (tour), “Once on This Island” (tour), and “1776” in my package. Buying all at once helps me plan for making the often-congested trips north to see the shows.