All hoods whether vinyl or mohair should always be kept in the fully locked position when not in use.
I don't doubt the wisdom of it, but this has to be one of the guidelines most often honoured in the breach than the observance.
Can I really see myself laboriously erecting the hood whenever I put the car back in the garage only to take it down again the next time I go out? It's just not going to happen. If it's wet when I get home I leave it up until its dry, but once it's down it stays there until it's needed again.