Wood shakes (wood shingles) were historically split from straight grained wood. Today they are mainly cut or split from wood. This type of roofing system was very popular in the past because of its durability and cost. Sometimes these types of roofs could last up to 50 years. Today this roofing system is not used that much since they are cut different they are not as durable and catch fire more easily than a similar looking roofing system such as a asphault shingle roof or tile concrete roof. Also they are more costly to put on these days than other roofing systems.
These days we do not put on this type of roofing system anymore but we do make repairs to them. This roofing system if properly maintained can last many years versus your standard asphault shingle roof. Keeping moss and algae off of this roofing type will keep this roof lasting a long time. Checking on a regular basis for damaged wood shakes and replacing as needed to prevent leaks.