One of the most important things you can do to keep your gutters functioning properly is to have them cleaned. Depending on how many trees and what type of trees are surrounding your home, determines how many times a year you should have them cleaned.
For example, if you are in a heavily wooded area it is recommended you clean them at least twice a year, sometimes more. Once in the spring after all the buds , seeds and nuts have dropped and in the fall, after the leaves have come down.
If you have underground drains this is especially important! Underground drains can be very hard to clean out. Once they get clogged it is very costly to replace them if they are running under your driveway or patio.
Another important reason to keep your gutters clean is that when your downspouts get clogged your gutters will hold water. That combined with the stress of the weight from the build up of debris overtime, and ice dams in the winter, causes them to sag and pull away from the fascia.
One way to tell if your ready for a cleaning is to go outside the next time it rains. Check the bottom of the downspouts to see if water is coming out. if its not coming out with good flow of volume, then its clogged. If you have under ground drains you should be able to hear or feel the water passing thru. If the water is backing up from your underground pipe then your underground drain is clogged.
If you have determined your downspout is clogged, the water will spill over at the lowest point which should be where your downspout is located.
If the overflow is occuring in the center or the opposite end of your gutter, then your gutter is most likey "backflowing" away from the downspout and will need to be re-pitched as well as cleaned.
Properly maintaining your gutters can extend the life of your system and prevent unneccessary damage to your home and landscaping.
I hope you have found this helpful.