Two quotes for the same elevation can differ by a third and both be honest. The difference is almost never the cladding — it is what each one is carrying around it: the scaffolding, the flashing, the transitions, whether the barrier is included, whether the deficiencies are.
What a rate per square foot cannot show
A square-foot rate is an average. It is accurate on a building with no corners, no openings and no changes of plane. Every corner and every opening is where the labour actually goes, and an average spreads that cost invisibly across the whole wall.
What a line-by-line price shows
The takeoff is read line by line: what is clad, what is soffit and fascia, where the transitions fall, and what the drawings leave out. That reading becomes the scope, and the scope is priced as it was read. A builder can reconcile a claim to a line without calling anyone.
Cladding by elevation and material, with the areas the drawings actually show.
Flashing and transitions as their own lines, because they are their own work.
Soffit, fascia and gutter as a separate scope from the wall.
The barrier and the cavity, stated rather than assumed.
It is more paper than a rate. It is also the only version of a price a builder can check.