The answer to 'how often to hedge' is that most hedges should be trimmed 2-3 times per year. Hedges need regular trimming to maintain their shape, density, and appearance. The frequency will depend on the type of hedge, its growth rate, and your desired look.
For fast-growing hedges like privet or boxwood, you'll typically need to trim them every 4-6 weeks during the growing season. Slower-growing hedges like yew or holly may only need trimming 1-2 times per year. Always check the specific care requirements for the type of hedge you have.