Laptops need cleaning more often than desktop computers, due to extremely narrow airflow tunnels. The quality of air and concentration of dust in your area are key factors.
Based on type of work, you should take it for cleaning with the following frequency:
- movie editing, 3D – 1 year
- graphic (mostly Adobe apps) – 2 years
- office work – 3 years
Regardless of the dust cleaning, repair shops will try convincing you to ask for replacing the thermal compound. Assuming the average lifetime of a computer is 8 years before buying another one, changing the thermal compound after 4 years is recommended.