I think that we have to keep things simple. I like to see that I have not troubles with complicated counting about what is efficient and what is too much around staff.. however would be great if there would be any possibility that staff get a speciality during his career in your club, but that possibility should not be made by any financial injections.
I thought something about experiences which that staff get - like trainer which grow drafted player for a season or during that season got better more than 6 players for more than 3 skillups.. so doctor taked care of more than 5 injuried players and PR had any average amount of balls on fan survey.. then they get any speciality (even if for half season or so before you fire them).
What I want to say is that staff can get experience under pressure, but these things they get for free, so they have to choose the wage for themselves.