I would suggest that this doesn't need to be an either/or.....but rather an "and". Having a secure run comes in handy in many situations and, generally, those situations arise with such suddenness that building one at the time is not really practical - situations like needing to confine the birds while addressing a predator that has shown up and started dining on the flock. Free ranging is fabulous, but there are times when doing so just isn't the best idea - so having a larger run where the birds can comfortably be housed for days/weeks without leading to issues associated with overcrowding is never a bad idea. Expand the run *and* free range them as much as is practical.