The 4th hint is not useful. I have two posts with almost equal author rewards (1st have 0.10$ and 2nd 0.09$). First one I made 100% sp and got only 0.05 sp. Second one was 50%/50% and I got 0.05 sbd and 0.02 sp. So it's better use 50%/50% option.
I saw post about this from another user (don't remember the author of post). He wrote that option 100% is useful only when steem fall very much.