Ideally, a player should be able to enter the number he wants -- the architecture seems to exist, if the random weird green speeds in brackets are anything to go by -- but I'd settle for 13 and 14 being added to the available choices.
It's frankly absurd that practice isn't available at the speeds the biggest events are played at. Club tournaments aren't a proper substitute, as the lack of mulligans doesn't allow for the repeated playing of a shot in different manners until the best approach is discovered.