In city builder games where you choose what needs to be done and wait for a citizen to finally do the job which you asked to be done hours ago. It would be nice to assign a character a task that they spend their time doing. When the work is done they idle around or do some other job till their given task becomes available again. With spending so much time doing their assigned task they get better at it and faster. Performing the task in 90% or even 80% of the time it takes a newbie to do.