Calendar spreads are low probability trades to begin with but that doesn't mean that we can't make adjustments that increase their likelihood of success should the stock move fast and one direction.
As with most of the strategies that we will adjust the mechanics will remain roughly the same, i.e. rolling one side of the trade to follow the market and collecting additional premium to reduce risk.
With calendar spreads in particular we will always look to adjust the front-month contract that we are short, moving it up or down based on the stock's movement. We rarely will touch the back-month contract we are long.