Originally Posted by SK AAR

Your experience at CDG is a very rare exception - maybe your original flight was overbooked?

LH is very strict on adhering to the rules; you will fly as ticketed unless your request for an earlier flight suits LH - and even then it will be an exception if LH accommodates you on an earlier flight. There is no such thing as "standby for earlier flight" on LH (or other European carriers if that matters)