I have quite a few groups where the guys served 14-18... but this one is unusual in that his service was never interupted. He went into the field in October 1914... and stayed in rgw regiment (Verdun, Somme, Champagne etc) until 1918, Left for hospital in April 1918, then officers course... but between those dates he was "there"...
From memory, all the other groups I have have guys being wounded, then off in hospital, then time at the ersatz Battalion, then on a course of some sort, maybe some time at the Feldrekrutendepot, many guys after 2-3 years were sent to work in a factory for a while (!).... but this is the only infantry Guy I have (as far as i can remember) that was in an infantry company, in an active western front unit, that spent 42 months on service (with leave of course!)