Agreed. It wasn't a waste of time. This is how professionals explore their options. They interview, ask questions, research, then make their decision on which company works best for them. And then they politely and professionally inform the companies they choose not to join, that they will be declining the offer.

Some companies may ask what the deciding factor was and then, if possible, they can address that factor therefore making themselves more attractive to the next applicant.

Good luck with whichever company you decide works best for you.