Ehh, including NW3? I've gone from NW3½~ diffuse thinning with heavy crown losses to like NW1½-2... And I have not even been on the meds for that long yet. Actually, my hairline is closer to NW1 right now but there's still some minor thinness in my crown.
So, to say that NW3 is too late - that is something I would not agree with. However, NW4 is pushing it, with the more important facet being the duration of follical inactivity. If one is balding fast, it likely means their hair loss will continue being aggressive to an extent, so regardless of Norwood-status, one might or might not have good results. If one is balding slowly but is late to act on it - the duration of follical inactivity might already have gotten to be too long for the meds to reach their maximum potential. Add in the luck of the draw with how good of a responder one is with the meds and we're getting there. I am a good responder and I acted within 5 years of balding. Someone else might not be as lucky.
So as you see, it's kind of random. Still, I would say that NW4+ and 5+ years of follical inactivity, both, in the balding areas would be potentially "too late", though you never know. Being a decent/good responder will change things. But that's also a matter of luck.
