The same install spec does not work across all 21 counties. Sustained cold in the limestone country and repeated freeze-thaw along the Ohio River are different problems requiring different attachment.
Our 21-county Indiana territory looks like one market on a map. From an installation standpoint it behaves like three.
The western and higher end of the territory, through Monroe, Brown, Lawrence and Greene counties, takes the longest sustained cold. The defining stress there is duration rather than depth: a run stays loaded and thermally stressed for weeks at a stretch. That compresses the booking window, so those properties should book on the early end of October rather than treating early October as optional.
The center of the territory, around Seymour, Columbus and Brownstown, runs a middle profile. Cold air, regular ice events, moderate snow totals, and frequent freeze-thaw cycling. Ice is the real adversary here more than snow depth. Ice adds weight and it works into any gap, and repeated freeze and thaw walks a marginal clip loose over a season. Clip density and wire routing get specified with that cycling in mind.
The Ohio River communities, from Madison through Vevay, Rising Sun and Patriot, are mildest on paper. Less snow, shorter cold stretches. But the freeze-thaw cycling is if anything more frequent, because temperatures cross the freezing point more often rather than staying below it. That is harder on attachment than a steady deep freeze. River communities also deal with humidity and fog off the water, which affects both summer install comfort and long-term corrosion on lower-grade hardware.
The practical consequences are worth stating plainly. There is no single clip spec that is correct across all 21 counties. A run specified for a Madison riverfront house is under-built for an exposed elevation in Brown County. A booking calendar that works on the Ohio River leaves a Monroe County property scrambling. Permanent lighting systems run essentially uninterrupted year-round across the whole territory.
This is also why regional experience matters more than brand when choosing an installer. The question worth asking is not whether a contractor has done a lot of installs, but whether they have done them in your part of the state, through your winter. Indiana gives you three meaningfully different winters to get wrong.