Might BBC News Fix be an insider working at BBC?
Then wouldn't he be able to go and look in the internal rotas and find all the vitally-important information for which he claims to have such a pressing need?
Here comes my refrain once again... the people doing these shifts and the people organising them don't pay this much attention because their jobs a) mean they simply don't have time and b) even if they did, they've come up with better and more productive ways of filling it because - say it with me now - they're respected journalists working for a 24-hour news organisation!*
* And before you ask, I'm on my holidays, and just want to help young people who clearly have an interest in the business not screw up their entry into it - if they do want to find a way in, this level-of-scrutiny will be a massive turn-off for prospective mentors.