I know what you mean - it's a lot.  But I think common sense can apply here and these are guidelines really.  If I were outdoors, midday in Hawaii and surfing, I would apply all that and more. I'd probably use the Elta MD water-resistant Sport and layer over that the Colorescience powder sunscreen (it really does stay on in the water!) and reapply often.   If I were walking in N.Y. on a cloudy day, I'd probably use the Elta MD Physical Block or SkinMedica Environmental Protection sunscreen and apply about 1/2 that amount (1/4 tsp) and maybe then put a little makeup with SPF over it.   If I were cycling for a couple of hours in the LA area, I'd probably use the Dermaquest Zinclear about 1/4 tsp (more zinc) and put the Colorescience over that as well depending on how bright it was.

This might be TOO complicated so I apologize in advance but my point is that - you can adjust for your circumstances and it's fine. Here is more information on these good sunscreens.    Dr. I