The sequencing argument
Drip edge, gutter apron, and the first course of shingles all meet at the eave. When gutters go on after a roof, the installer works around finished shingles and fasteners land in a completed edge. When they go on as part of the same job, the flashing laps correctly the first time and water goes where it's supposed to.
What insurance usually covers
Hail large enough to bruise shingles nearly always dents aluminum gutters and downspouts — and those dents are frequently the collateral evidence that proves the storm. Most approved hail claims include gutter replacement in the scope. If your adjuster's estimate omits them, that's a supplement, not a loss.
Sizing for Colorado runoff
Front Range summer storms deliver a lot of water in a short window. On steep pitches and long runs we size up to six-inch seamless gutter with oversized downspouts so the system actually keeps up, rather than overshooting and dumping against the foundation.