My waters broke over a week before my planned CS date, and they just did the CS earlier. I went in to hospital, they told me to come back next day (I wasn't having contractions), and then did the CS then.
I had to wait for a slot in theatre, as they had EMCS/instrumental deliveries a go go that day, but that would be the same whatever day a planned non emergency CS was scheduled for.
This was a scenario I'd discussed with my MW (going into labour before CS date), and she wrote it very clearly in my notes that I was to be given a CS if I went into labour, no 'trial of labour' etc, and she told me to get to hospital if I suspected anything was kicking off, and not to wait. From the hospital's POV, they don't want you arriving in active labour and them having to rush to fit you in somewhere. And you don't want to risk (the very small risk) of labour progressing so fast it's too late for a CS.
I think with length of labour, it seems to depend on the individual hospital, what the labouring mother wants, how she is coping with tiredness/pain etc, and most crucially, how well the baby is coping with the stress of a long labour. I've read women complain about being 'rushed' into a CS for failure to progress - I've had friends who are very angry and upset that they were allowed to labour for so long before the decison was taken to go to CS. Different expectations, different perceptions I guess.