85 dB SPL (C weighted) will sound quite a bit louder with pink noise compared to music itself. So I prefer to set the overall SPL with music, not noise. One does not listen to noise generally.
85 to some may sound fine compared to others. They say that at 85 dB SPL the ear approaches the most even response.
(note approaches! it is never flat) I have never really got the concept of only using 85 in large room. To my mind the room size should not matter too much. 85 is 85 arriving at your ears, room size or not. I guess though that pumping 85 into a smaller room may tend to inject more energy into a smaller room compared to a much larger room. Which can be problematic for some smaller rooms.
The best way to keep an eye on SPL levels in your room is with a permanent SPL meter setup roughly in the sweet spot and telling you all the time how loud things are there. Overtime with a long mix your SPL levels can creep up because your ears are getting tired and shutting down slowly. It does keep you honest.
Some around here are saying they cannot monitor at 85 and they are monitoring much lower e.g. 75 dB. This will give you inaccurate picture of what you are hearing. At lower SPL levels your ears are less sensitive to low and high end which then may make you push these a little more which is also not good either. You also need to check at loud volumes too e.g. 95 and 105 dB. That reveals other stuff such as bass, kick and reverbs etc..