My strategy is, only to sell if I have to. No matter what price it is then. It does not make sense to sell for fiat money if you dont have to, since the whole point of bullion is to preserve value.
Well, may be, selling to buy property could be a concideration, since that is also a way of securing value - if it comes at a price you cannot say no to.
But else, I only sell if it is really neccessary.