I heard rider fatigue mentioned which kind of makes sense given that they had afternoon and evening practice on Friday, practice session and 2 races Saturday and 6 laps on Sunday.

I've often questioned why the never move races forward and always get told you can only move back, not forward, but I could swear a few years back at the 'old' Manx GP they brought the Senior forward to the Thursday over weather fears and lack of marshals.