Its a way for the RRC to let you know of issues that may exist with the program (generic, usually) and set a timetable for their return.
Example: we had a 5 year accred when i showed up in 2006-7, RRC that year found some issues, knocked us to 2 year, came back in 2009, saw everything was legitimately fixed, and we were back at 5 year.
Its obviously an issue to not be 5 year if the program isnt working on fixing things, because long term complications can result, but its very unlikely that a top program wouldnt make it their #1 priority to fix any problems. Its probably better to come into a good program on 3-year cycle than on 5-year cycle, when you think about it.