You can minimize the risk of clogged downspouts by (1) keeping your gutters clean, (2) using pop rivets instead of galvanized gutter screws for the first elbow, and preferably the second elbow, 3) if you must use one or more galvanized screws, snip/grind/file off the sharp point of each screw before inserting them to minimize the risk of the sharp point snagging debris, and 4) use two 45 degree elbows connected by a short length of downspout, rather than two 90 degree elbows (which tend to restrict the flow more).
You can clean the gutters on your house with the Gutter Viper without having to carry the leaf blower with you - this technique allows you to leave the leaf blower on the ground behind you.
It is good practice to clean your roof valleys of unsightly debris that will eventually damage them if it left for long periods. For example, galvanized metal valleys will rust under clumps of wet, matted, debris.
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