Originally Posted by RH Clark

Why do you think that? What's needed is enough gradual adaptation to reach a goal. If you go to failure, then take time to recover, you often need much more recovery time. The extra recovery time becomes detrimental. Besides that, you wind up getting very sloppy in form toward failure. There's a greater chance of injury. Perhaps to the failure of perfect form and control might be closer to what's necessary.

Look at it in terms of specific reps done with specific weights. If you wind up with more reps over time because of less time off for recovery or injury, chances are you get greater gains.

As far as whether or not you failed, only you get to decide. I say you are doing very well in just the attempt. At least you didn't kill yourself. Sometimes I think it's good to listen to the voice that warns us to back down.