Re: need some resources for natural birth
I don't know the circumstances for your inductions, so take this with a grain of salt. But, I am a big believer that if your wait for your body to go into labor naturally, then your labor will be shorter than if it was induced before your body and the baby were ready for labor. With my first and only dd, I was 14 days overdue and if I hadn't selected a supportive midwife practice, most doctors would have been pressuring me to induce. Although I had about an hour of mildly painful contractions every night during those two weeks of waiting, my labor never took off until my water broke, and from that point I dilated from about 2/3 to 10 in 4.5 hours, and delivered my baby after another hour and twenty minutes of pushing.
Most women will tell you that subsequent labors get shorter. I've read a birth story here and there where there was some glitch (bad positioning, etc.) and a subsequent labor ended up longer. But in general, they are shorter.