Tactical dynamic asset allocation or rebalancing based on valuation can be employed but this sounds easier than is practical, except in extreme market situations.
Tactical dynamic asset allocation or rebalancing involves selling at the right price and buying at the right price based on valuation.
Assuming you can get your buying and your selling correct 80% of the time;, to get both of them right for a profitable transaction is only slightly better than chance (80% x 80% = 64%).
Except for the extremes of the market, for most (perhaps, almost all of the time), for such stocks, it is better to stay invested (buy, hold, accumulate more) for the long haul.
Ref: My 18 points guide to Successfully compounding your money in Stocks