I agree with Feeling Broody. Mine seem to have a good sense of when I'm in, and they are usually always queuing up at their door. So I have been surprised when I have caught them unawares, that they are all ambling quite happily round the pen.
Hillfooter - is it alright, as a rule, to leave them outside all day whilst I'm at work, if they are within an electric fence? I think I would worry (though I'm not sure about what).