I think it depends on your skin tone. Black people can get a lot of sun without burning. White people evolved in a cloudy climate and need less sun for the same health benefit (and also burn very quickly in midday sun in not cloudy climates).
If you maintain a base tan (equivalent to 2 hours in the sun or 10 minutes in a "standard" tanning bed, per week), the melanin is highly photoprotective for any additional UV exposure.