To add...you're budgeted 50 days to complete the IFS syllabus. Some people take 49 days, some people (like me) finish in 17. It's not really an at-your-own-pace thing, its just how much your instructor can fly you, weather, other students that need to be pushed through, etc. Its the same curriculum (FAR Part 151, if you're interested) but the amount of time it actually takes varies widely.
Time waivers are possible, however. I started IFS 3NOV and finished 7JAN because of Christmas/tons of days of crappy weather.