The answer to 'frequency of tree' is that the frequency of tree maintenance and care depends on the type of tree, its age, and the climate and environment it is growing in. Generally, most trees should be inspected and maintained on an annual or biennial basis to ensure their health and longevity.
Young, newly planted trees typically require more frequent watering, mulching, and pruning to help them establish a strong root system and healthy structure. Mature trees may only need periodic pruning, fertilization, and disease/pest monitoring every 2-3 years. Trees in harsh climates or urban environments may require more frequent attention to address stress factors and potential hazards.