De ice
With a CPL and IR I think your instructor is taking the michael. You would have done them in a complex single. In my experience pepole who go over the 6 hours generally do so as they are taking time to get used to wobbly props and gear etc, not to mention bigger weights and higher speeds.
In saying that then most people are correct. It depends on what you've flown. If your 100 hrs are in a 152 then I doubt you would do it in 6. Eight may be a realistic target. Otherwise I don't see any reason not to expect it in 6.
Good luck