I have snapped a couple after noticing rail cracks just in front of rear straps, Ben Wilson pro slingshot and North Contact.
The reason Is that flat landing for what ever reason on a surf board is bad

seems to be a weak point, thats were all my surfboards snap too from regular surfing. Most riders have most of their weight on the rear of the board for control so boards snap at the stress point or fulcrum closest to rear foot.
A tip from me would be that if you feel like your going to land flattish, try and correct by lifting front leg or powering up a bit or just bail, boards are so xxxy

no jumps worth a grand for us regular folk.
Reason I have never snapped a board unstrapped is the board is never horizontal as you need some vert to get wind to hold board to your feet. and I'm no good and enjoy not having to worry about the board when in the air.

more fun for me ATM