at the moment their is only six character slots for each accounts and their are seven schools so you have to leave one school out, so I reckon it would be a good idea to add a seventh slot do you can play each school on a account.
I think we should be happy that we already have the opportunity to play this game six different times with six different characters with six different abilities and play styles. More than that if you consider we can delete and replace characters at our discretion. As someone who is currently playing with a full complement of six wizards I can tell you it's a bane and a blessing. It gets to be a chore sometimes to remember which character is doing what where. Adding a seventh slot isn't a necessary addition and would actually add to the confusion. I realize that when you spend a lot of time developing a character it's a tough decision to delete them. You can always start a new free account and try out different schools on a limited basis. Running a wizard through the Wizard City story line will give you an idea of whether or not you're going to want to play that school through the entire story.
Yeah, Sam said it, this isn't going to change. Six is good. It impesses upon younger players the importance of an educated choice - because there is always one school you can't enroll in, so look into them to see which you want.
actually, there is a POSSIBILITY of a 7th slot. I dont remember where I heard it, but I BELIEVE it was on the KI Live event within the past year or so, that they were talking about the reality of doing this, and if it would cost crowns or whatnot, but that was the last i heard about it. Im not saying it will or wont happen, should or shouldnt happen, just that it was made public that they TALKED about it internally
As has been stated, KI is not going to add a seventh slot but you can do like a lot of us do and create another account(s). I myself use 3 accounts, 2 paid and 1 free. I use the free account to test ideas and the other two accounts to play.
I'm also one who will not delete a character I've spent a lot of time developing, even if it turned out to be a bad combination idea. So creating another account under my Family's account let's me continue making good and bad school choices for my growing student population.