Your LP should almost always be the same and is unique to you. So, some women may have a 12 day lp, and some may have a 15 day lp. (the average being 14) but it is the same every cycle. What CAN change is the day you ovulate, usually only by a few days though. SO if you Normally O on cd 14 and have a 28 day cycle then if you were to O on cd 9 you would more than likely have a 23 day cycle. Hope that helps