I have a family history of skin cancer plus askin condition that looks bad if it tans so I am pretty diligent about sunscreen. My kids have nice Italian skin and have never even gotten pink (although in part also due to my sunblocking I'd like to think). My DH refuses to sunblock himself at all and is terrible about ever doing the kids. So anyway, realistically, here is what I do - intending to really do it well, but sometimes forgetting and DH never thinking about it....
I coat all 3 of us heavily with lotion in the AM, entire body, even what is covered by clothes (not under jeans in winter). I pack 2 big tubes/bottles of lotion. I use spray to reapply 2-3 times during the day - just exposed areas. I pack 2 bottles of spray. I also use one bottle of just face that I use in am and reapply- I pack smallish bottle of this. I come hone with about 1/2 of one tube and 1/2 spay left. I think I use more sunblock, especially the reapply than others.