Out of my 4 pregnancies, they are all a bit different, but 3 a little more alike than the other....the one not as similar pregnant one was the most beautiful chart I've ever ever seen! I'm sure it helped that it was when i had no other children, so I got perfect sleep every night! I had such nice and steady temps pre O and post O, a beautiful spike after O, with a nice triphastic in the LP....blah blah blah.
My other 3 pregnancies had a lot more variation in them. The two consistant things here were a nice spike in temp after O'ing (great for confirming O!) and a very low dip (too soon for implantation for one cycle IMO, because it was 5 & 6DPO with DD, but at 12 & 13DPO I was still getting BFN's). But the other two I guess it was possible, one was 8-9DPO and the other was at 9DPO. These dips went below the coverline or uncomfortably close...each time I thought, OH MAN, this STINKS! So, with these 3 pregnancies, the main thing was the variation in temps and the not prettiness! LOL! But, I did have nice temp spikes for confirming O...which is why I'm not confident for my current cycle!