While levelling, I got to the 30-point tier of the BM tree, and picked up BW and 3/3 CR, and figured I might as well put my 5th point into FI. Now, since SS > FI, at level 45 I started putting points in there. But I noticed that the tooltip wouldn't change from 1/3 to 3/3 on FI, it just says "increased damage." So for grouping, people see that and think they're getting the full benefit, when I can get 2 extra talent points to use elsewhere...
Granted, it's not a great trick for end-game stuff, but for levelling+pugs my party will like me for it and I get 2 free talent points.