Absolutely it is encouraged. A hair demo is basically a trial run for your wedding day hairstyle. This is an opportunity for you to sit down with your stylist and discuss what kind of look you're going for on your big day. They'll be able to give you some guidance and help you choose the perfect style. If you're undecided about your wedding day hairstyle, or if you just want to make sure everything goes perfectly on the big day, then scheduling a hair demo is definitely a good idea.