Two different low bands
Low is 35-43 and Critical is 21-34. Both are roofs close to the end of their working life, and both still have options: Boost on its own, or Boost applied with Fortify as a two-coat system.
Boost is 5 years on a prorated basis. Boost with Fortify is 10 years with full coverage for the whole period. That is a meaningful difference for a roof that is worn rather than finished.
Where the answer changes
Replace begins at 0-20. There the table offers the Boost bridge for 3 years and nothing longer, because there is nothing left in the surface for a longer term to stand on.
That is the point at which the honest advice is a new roof, and a bridge is only worth buying if you need time to arrange it.
Things the score is not deciding
A leak is a repair job whatever the score says, and it comes before any treatment. Missing shingles, soft spots and failed flashing are all dealt with first. If the leak points back to a roof that has reached the end of its life, replacement is the answer regardless of band.
The same goes for the material: a metal roof is not eligible for this treatment at all, so its condition never decides anything here.
What the visit settles
The assessment is free and it ends with a written estimate that names the treatment, the scope and the price. If the roof should be replaced, you will hear that at the visit rather than after work has been scheduled.
There is no obligation attached to asking, and no sales visit theatre: one short visit, one scored roof, one written recommendation.
What a low score is not saying
It is not saying the house is in trouble, that the deck is rotten, or that anyone has been negligent. It is saying the shingle surface has lost the material that made it work.
Those are different statements, and only the last one is ours to make.