>>30034421My friend has chained five shinies via SOS.
4/5 have at least three perfect IVs. The 5th one was a shiny she got in a chain under 10 so it only had one perfect IV.
One was in the 50 range, four perfect IVs, two in the one hundred range, four perfect IVs, and one around 400 which had only three perfect IVs.
So, 50 is probably a guaranteed three perfect IVs. (I assume the 4th ones were just random strokes of luck, given the highest one had only three perfect IVs) I wouldn't be surprised if the actual number is lower like 40 though.