Off-season double-bricks anyone ?

My first triathlon off-season does not really qualify me to comment on this. But my idea of an off-season is where you can have unstructured fun, work on your weaker disciplines, build a solid base, and .....experiment a little. How about the occasional double brick (eg, run/bike [am], and then swim/bike [pm]) ?  As long as it isn't too intense. Has anyone tried this, would recommend it, or it shouldn't be touched with a barge-pole ?