As an UX-Designer one of your core abilities is knowing and properly using your creative techniques.
There are multiple techniques that can be done without your users. You as an UX-Designer can create some first ideas which can be used for more creative techniques with your users.find out more
There are creative techniwues available that can be executed with just one user at a time. Those are beneficial if you want to understand the ideas of a single person.find out more
Often it is useful to work with multiple users in a creative session because they can influence each other and therefore generate new ideas together.find out more