If you’re asking for numbers (frequency, sets, reps, etc.) you don’t understand the principles that they are supposed to represent. The textbooks and “research” are generalizations that do not consider beginners, progression, degree of effort per final rep, learning the skill of the exercise, etc. People ask “can you work ‘core’ every day?” They obviously don’t understand that frequency is directly related to effort, volume, recuperation, etc. It is not related to specific days or even that a week happens to have seven days.