The answer to 'frequency of shrub' is that the frequency of shrub trimming and maintenance depends on the type of shrub and its growth rate. Most shrubs need to be trimmed 1-2 times per year, usually in the spring and fall. Fast-growing shrubs may need more frequent trimming, while slow-growing shrubs may only need it every 1-2 years.
The best time to trim shrubs is in the spring before new growth appears, or in the fall after the plant has gone dormant. This helps maintain the shrub's shape and encourages healthy new growth. Be sure to prune just above outward-facing buds to direct growth in the desired direction.