Corners take the abuse
Most gutter leaks start where water changes direction. A carefully built miter gives sealant, fasteners, and metal overlap a better chance to hold up through freeze, thaw, wind, and roof runoff.
Fit matters more than flash
A sharp-looking corner only matters if the pitch, overlap, and seal are right. Good installation reduces standing water and helps the system move runoff toward the downspouts.
Ask about the details
When you compare gutter quotes, ask how corners are handled, what sealant is used, and how the contractor checks for flow before leaving the site.