Are programs intended to be used multiple years in a row?

No. Most programs are a single 36-week, year-long course. Because Sonlight is literature-based, each program works for a range of ages/grades, but each program is designed to be used for one year with one or more student in an age/grade range.

Another benefit of Sonlight: You can easily reuse the same program with a younger student (just get extra copies of the few consumable items).