Winter weather can alter the gutter pitch causing problems.
Below are the guidelines for the “perfect pitch”.
Gutters may look perfectly even, but it’s a carefully crafted illusion. Gutters actually have a slight pitch that allows water to flow towards the downspouts. It’s very gradual and not noticeable, but it helps sweep away debris and keeps your gutters clean, and allows water to flow to the downspouts without overwhelming them, thus backing up the system Gutter runs 30 feet long or more should have a downspout installed at each end, pitching the gutter from the center towards each downspout.
Experienced gutter installers know how to pitch the gutters. Many times they will use a level to insure accuracy. Sometimes the structure on which the gutters are installed, will determine the appropriate amount of pitch to have the gutters work efficiently.