If they don't already have one, I reckon they should have a two-tier ballot system. One for "Tier A" games where there's extremely high demand and/or low availability (Hearts, Hibs, Aberdeen, celtic). One for "Tier B" games where there is a high supply of tickets and/or relatively low demand. Then you don't get someone missing out on one of the top games because they got one against Killi and St Mirren. You could even have a "Tier C" where there's no ballot at all but available to those on the CCCS/Away ticket schemes on a first come first served (e.g. Kilmarnock).