It isn’t uncommon for me to spend 3-4 hours outside during the afternoon...in Tucson, in summer. I primarily use sunscreen on my face, where I can burn and blister very easily.
I use the tan rule. If I tan without burning, it is OK. For an hour, I can handle most anything. Times longer than that deserve some help.
Sounds reasonable. People that are of a pure Celtic type (the people with red hair and freckles) are the most vulnerable to skin damage; it is an individual issue. I am—like most Americans—a mutt with Celtic, central Euro and Semitic genes, so I can take more sun than the redheads.