Royal Caribbean allow you to use your formal dining table as and when you choose. If you don't fancy formal dining one evening you can dine in the buffet restaurant and dress far more casually if you so esire.
Absolutely one OR the other.......and if you sign up for Mytime dining you have to prepay your gratuities.
Just count yourself as being lucky that you have the option to choose. Opting for both would so complicate the system as to make it unworkable. .......Neil.
What is Mytime dining been on Explorer of the seas and have not come up against it ?