Inbreeding, how many generations should be skipped?

[Stewart_Reptiles]

I usually breed 2 generations maybe 3, I always old back some of the females I produce for future breeder (I hold them back based on temperament of the mother and whether or not the mother is/was a good breeder) and every 16/18 months or so I retire the males and buy some new ones to add new blood in.

So I don't really count I just have that routine going