Where seams fail
Sectional gutters leak at couplers after freeze–thaw cycles. On a 60-foot run, that is three or four weak points every decade.
Seamless runs are fabricated on site to length, with seams only at inside/outside corners and outlets.
Size and outlets matter
Oversized gutters without enough outlets still overflow in July thunderstorms. A scope should name gutter size, outlet count, and downspout paths — especially on homes with shallow roof pitches in Salem and Pelham.