I stay around 15-17 watts most of the time, and I rarely ever just set around and chain vape, I vape like I used to smoke 4,5,6 draws every hour, vtc4 will last me all day with 70-75% left.
With my Eleaf Lemo 5ml of juice will last 2 days, of I'm using a kayfun about a day and a half per tank.
Personally, for my vaping habits, and the juices I vape I I cant find any benefit (Flavor, vapor production or throat hit) to crank the wattage up that high.
BTW I typically run 1.6-1.8 ohm coils so at 17w I'm already at 5.21v plenty warm enough vape for me.
even if I'm running .9 to 1.2 ohm dual coil build in my magma 17w would be max. 20w would be like vaping superheated steam IMO.