I put one point into Survivor's Instinct after it became available, and found it handy to top off my health whenever I went to trade or drop loot off at my base. It wasn't fast enough to encourage me to keep putting points into, until I reached the wastelands and had all kinds of spare skill points. I maxed Survivor's Instinct and that was just about the only healing I needed for the rest of the game.
Ranger Sight is useless compared to Elven Sight. The only reason you should put anything into Ranger Sight is if you want to clear the fog of war in areas you can not get to, and have already maxed (or plan to) Elven Sight.
True Shot is broken (as of v1.34 patch), so that counts as useless.
