Hey, I'm looking to buy a ND filter pack. I'm noticing that a lot of packs, including Polar Pro, are offering ND4, ND8 and ND16.... My experience with Mavic Pro is that ND16 is most used, and ND8 and ND32 are used for cloudy or very sunny days. So I can't understand why the ND 8, 16, 32 isn't the default for a pack of 3 ND filters. Am I missing something here? Is the ND4 actually useful or is it just a marketing ploy to get you to buy a multi-pack and then need to buy a ND32 separately.