Yup... i did the same thing before (keeping the 9-lvl gap) since lvl 14. But when I reach lvl 20, sp farming is starting to be a little drag (maybe i grew bored about it). So I closed the gap further to 6 and maintained it that way. Currently, I have 6K++ sp (lvl 27). I think if I maintain this throughout the game, leveling my character will not be that slow to bore me and at the same time, earn more sp.

I think maintaining this way of farming will be sufficient enough for players having 1 weapon - 2 force masteries. I don't know if the is will work for players having more masteries.