Fixing minor roof problems before they become costly is a very good way to prevent more severe damage to your roof and reduce home maintenance costs.
You also need to be aware of the aging and weathering of your roof - know when is time to replace it.
Most experts agree that is a good idea to check regularly your roof at least twice of year, ideally in spring and fall.
Check your roof in fall to prepare for the winter - it is going to be more difficult to fix the roof in bad weather when is cold or you have ice and snow on your roof.
Check your roof in the spring to find if the winter damaged your roof.
Another good time to do a roof inspection is after a severe storm.