I've also seen flights schedule that could never be on-time.
Last Sunday I took a SEA - SJC flight, and the incoming was like: ONT - PHX (land around 5:00 p.m.), then PHX - SEA (schedule to depart around 5:00 p.m.). No way they can be on time.
And that delay was announced in the morning (not caused by some sudden mx/weather issue).