Cardiology and dermatology compete against different rivals for different patients. One pooled figure hides which programme pays.
A single institutional marketing line is the most common reason hospital boards cannot tell whether marketing works. Averaged across eight departments, a strong programme and a failing one look identical.
Split the budget the way the P&L is split. Each department gets its own objective, its own capacity ceiling and its own reporting — an oncology programme measured on qualified consultations, an outpatient department measured on filled slots.
Capacity comes before spend. There is no value in generating orthopaedic enquiries the theatre cannot schedule for six weeks; that budget belongs to a department with room.