PHOTOGRAPHS FROM OUR OWN WORK
What this looks like in practice.
Notice where the water escapes
Overflow along a run may indicate a restriction or standing water. Overflow near the outlet can point to a blockage there or further down the pipe. These observations help an inspection but do not establish the cause on their own.
Consider the whole drainage route
We look at the gutter, its supports, the outlet and downpipe. Guards may conceal debris, and a clear-looking gutter can still have a restricted outlet. The proposed remedy should address what is actually found.