In Western riding, do you post or sit the trot?

You will usually sit the trot for Western, but it is still important to know how to post as when a horse goes into a big trot, it can be very difficult to sit. Being able to post is just a basic riding skill; even it isn't used much in Western, it is still good to know. For example, if a horse breaks from the canter, they may throw in a few fast strides before you can put them back together--being able to post will allow you to stay with the motion and not get jarred around.