I started taking B6 last cycle after discovering I had a short LP two cycles ago. It definitely helped. I ovulated a day earlier, and I got a BFP. Unfortunately, I had an early miscarriage. My doctor doesn't think it was related to my short LP, but we really can't say for sure.
However, I'm confident that the B6 helped, and I'm hoping it helps even more this cycle. I figure there's no reason not to take it.