I have a friend doing research on this. I should caution that you should in no way take this as medical advice, as there are not yet any results, but the current hypothesis is that one's risk of getting melanoma (the main skin cancer that is truly dangerous) is actually less related to how long you stay in the sun and instead more related to whether your sun exposure is consistent (each day) or intermittent (you only go out in the sun a couple of non-consecutive days a week). If this hypothesis is correct, consistent sun exposure is significantly safer than intermittent sun exposure.
If you would like, I can provide links to papers that support this hypothesis.
I asked because I just started supplementing with vitamin D and forcing myself to get 15 minutes of direct sun exposure every morning since I started working/exercising indoors at home and rarely venturing outside during the work week.
That is something I would like to look into and appreciate a link if not a hassle. That hypothesis could change how I go about my daily exposure. How much exposure do you get if you don't mind me asking?
If you would like, I can provide links to papers that support this hypothesis.