I think taking a lot of sets to failure is definitely necessary for muscle growth.
A lot of times when I am lifting, I'll either ramp and take my top set to failure, or if using straight sets, I will take every single one of those sets to failure as well.
When it comes to strength gains, taking sets to failure everytime you are training is often counterproductive especially when you begin to move very heavy poundages that are really taxing on the nervous system.
For your incline bench I would properly warm-up and ramp up to an 8 rep max. I like ramping because it allows my body to become accustomed to the movement (groove) before I hit something heavy and also gets my muscle/joints/tendons properly warmed up to help avoid injury. There comes a point where your warm up weight and 8 rep max are significantly different and if you go from benching 135 to 315 as your next set, the risk of injury is also increased. That's why I like ramping.