Theoretically I imagine second labours are shorter because the body has done it before and is 'primed' so to speak. I remember reading that in subsequent births, the hormones that induce labour are more effective because the receptors have been set by the first birth and it makes the whole process of hormonal response/birthing much more efficient. The body knows what it is doing IYKWIM.

The thing that might make it slower is a malpresentation as MadB mentioned or maybe a psychological barrier like an unresolved issue or a feeling of not being 'safe'. Then, you can't always bank on your psychological state slowing things down.

Based on that, I imagine that having had an induced and supplemented birth should not make a difference. Your body still went through the motions, still responded to the hormones, still had a good go!
This is the thing i am trying to work out, are the hormones released and do they do the same thing if the labour is being controlled by artificial syntocinon? Would my receptors be activated by my first (induced) birth similarly to if it had been a natural labour?

I was induced at 41 weeks due to APH (bleeding), but was already at 4cm dilation when it was started. I didn't feel safe, and i know this probably slowed things down (cos i just wanted to go home) but the drip had to stay on for the whole time. The drip was going for 12 hours when bub was born.

So, my body has been through it, but if the drip was required the whole time, then i presume my hormonal stuff didn't kick in properly.