How often gutters need to be cleaned depends on the part of the country and whether there are nearby trees. If you live in the Arizona desert, you may be able to go several years, but for those who live where autumn leaves fall, it's important to clean gutters at least twice a year.
The most important time is in late fall after all or most of the leaves have come down. Most deciduous trees also drop debris in the spring, so an early summer cleaning is important as well. Those who live in heavily wooded areas may find it necessary to clear the gutters three or four times a year.
Always make sure the downspouts are not clogged and that they are carrying water away from the house foundation.
Gutter guards and screens:
There are several products on the market that reduce the need for maintenance, but do no eliminated it entirely. Some gutter guards are made of a metal mesh intended to keep leaves from getting into the gutters. Another method is a foam insert that fits inside the gutter. The foam is highly porous, so it allows water to flow through it to the downspouts while keeping leaves out.