one good thing about having a short position mixed in amongst mostly longs is that when we get these types of weeks there is some part of your portfolio that benefits from the gloom and doom.
Thats why I like to have them (shorts) when it seems appropriate -
I think we discussed this sometime before with regard to exposure to the retirement sector whereby if you had , say short Ryman position, you could go extra hard on your long in say OCA because the sector risk is somewhat mitigated.