Frequency of gutter clean up will always vary from property to property. Homes surrounded by larger more full trees could require 2 to 5 visits a year. Even properties with less trees but the right type of tree like Pine trees could require this also since they drop extensive amount of foliage through out the year. Homes with less trees usually get by withe just one visit once all the leaves have come down. Unless a home has gutter guards you want to make sure to have your gutters clean our yearly to prevent possible damage to the structure of your home. Gutters that have blockage issues create water flowing to areas that it isn't supposed to and water damage bring mold which can be a very high cost to repair if left for to long.
Homes with Gutter guards still need to at least be check yearly to make sure some of the smaller debris has not created a blockage. With the right combination of debris at the top of a down spout can create an issues with the smallest amount of debris.