Personally I think interspersing action with reaction is key but keeping the reaction balanced and not slowing things down too much. if you're writing a fast paced chase scene for instance, the reaction should be almost instantaneous and rapid, quick thinking on the move. Once the chase scene is at it's conclusion, a more drawn out reaction to decide who to chase next and why. One big thing I do see a lot of is having action and reaction in linear sections. So initially lots of bad things happen for a while and the reactions are generally wrong, then when the bottom is hit, everything switches, everything that happens is good and the reactions are spot-on until the final climax. Much better to throw things in that work the opposite way to the trend. It makes things more interesting and more realistic.