Kenton, the t-locks generally have hail damage as was mentioned in the pocketed areas of the shingles where they lock together. I went up on a roof with an insurance adjuster to have him point out the areas of hail damage once. He is generally looking for 7 dings a square to replace a roof, less for repair. In the soft area of the shingle that has been impacted there would be aggregate lost, and you can feel the impact damage in the mat. If this is not repaired it will become a hole that is obvious in time. The flat surfaces ( no pocket ) is harder to tell and to feel the mat damage. I always look for the other evidences as gutters, awnings, roof vents, flashings, chimney caps as well. You are looking for consistency. Also consider this, a house that is sold that has collected insurance money for hail damage and not repaired…that roof is not insurable for the next buyers until the roof has been repaired or replaced.