How many people here actually do extended OCI's? A few. I ALWAYS ask my customers if they are going extended OCI 10K-15K+. You do make a good point about extended OCI. I believe Amsoil does well as it reaches capacity and has a better capacity.They don't buy the high efficiency Amsoil filters to go along with their high mileage oil? Doing long OCIs while running a low efficiency oil filter isn't a good combination.
5K oil change? Heck you just said the same.
What car/engine? Driving habits? OCI? Sump capacity? Climate? All standard questions.
You can use the mean efficiency filter and not be afraid a a buzzwords such as "debris being ground between moving parts".
Point of all this?
99% filtration @20micron or 99% @15microns EITHER will be just fine for 5K miles. Total Overkill! Show me a study that proves either would be better.