An engagement session is an ideal trial run for the wedding day in terms of flow. Couples will understand more how long it takes to produce great images and how much time they will need for couple’s photos on the wedding day itself.
It’s also a great time for you to get used being in front of the camera and for me to see which angles advantage you more. Grooms usually are more camera-shy, but end up feeling quite comfortable towards the end. And getting dressed up can be a nice break from wedding planning!