I think the lesson here is, snakes are gonna do what they wanna do! I've got a big girl that has been breeding, off and on, since august 2010. At one point in early summer of this year it seemed like she was ovulating, but I guess she reabsorbed, because she got back to normal size and never laid. Both she and her mate have been eating pretty regularly. But now she hasn't eaten in 3 months... who knows?? LOL
On the other hand... I've been told, forget about breeding when they are in shed:
The het G-Stripe girl in this pic is blue as can be... and they are locking up!