It depends. Between sickness, job changes, stupid programming, lack of sleep and food, I stayed on intermediate programming for five years. I don’t have enough experience with advanced clients to make a hard statement on it.
As far as your programming, have you tried rotating reps while still on a 4 day split? You can do this with a two week cycle, a three week cycle, or more.
I see no reason not to keep a 4 day split as you get into advanced programming if it worked well for you in intermediate programming.