We considered including this one as a core activity that your dog ought to learn, but we included it in the additional activities section because it develops a somewhat niche skill; if you'd like your dog to one day have the ability to sniff someone out from miles away, then scent training would definitely be a necessity. For anyone else though, it's definitely more of a novelty skill. If you want to try it out, you'll to get a hold of some scented items (lavender or cedar smells will do the job) and then hide them so that your dog can find them.
Our thoughts on this activity are very similar to our thoughts concerning scent training. However, while we feel that training your dog's ability to smell really good is a somewhat niche activity, we placed obedience training in the additional activities section because most Dutch Shepherds are much more well behaved than other dogs breeds naturally. That being said, obedience training isn't too hard to do manually; you'll need a leash, some dog treats, and your dog's undivided attention to do it but it's possible.