Being too busy doing the day job to allow you to do any secondary duties is, apparently, also, OK. But your ROs must say this in your F6000/OJAR - something along the lines of "Bloggs is in a high pressure post which involves significant time away from base on ops/staff visits/liaision etc and consequently has had little opportunity to take on a meaningful secondary duty." I've been in jobs where I was constantly away and my ROs put this in and it seems to have done the trick.