I have been trying for so long to get certain strains from tude that just seem FREAKING IMPOSSIBLE. I've been after Serious Seeds ak47 Feminized (don't feel like doing regular for this strain) Gage Green Seeds Grape Stomper, and OB Ripper for so long. I even signed up for the auto notify when back in stock 2months ago and still nothing. I don't care how often I get on tude I NEVER see them in stock. Do they get them every now and then or do they really sell as fast as they get them?
First of all, there are other places that sell beans other than Attitude. Even when all the other banks are out, in some cases you may have some luck contacting the breeder directly and asking for beans. Sometimes breeders themselves have some inventory when the retailers don't.
I don't think any breeders are refreshing their stocks in 2 month intervals.
Commercial seed production takes at least a full three months starting from clone, going all the way through flowering to the point where the beans are mature, drying them, doing QC on the beans to make sure they're viable, packaging them for retail, and getting them dropped out to the third party se-ed bank retailer. For some strains/crosses, flowering times are longer and it takes longer to make the beans.
All breeders are up against space limitations, and some will only do se-ed runs during irregular periods when they have available indoor space they're not using for active breeding projects. Some breeders like to make their beans outdoors, and that means only one drop per year. In some cases, the breeders do rotations, and may create se-eds less often than 1x/year. Sometimes individual se-ed runs fail QC and the breeder has to do another run before they can be released.
Some of the breeders just put out small runs. . .they don't drop se-eds often, and when they do its in limited quantity, so they do sell out fast. Bodhi is known for this, and I think Gage Green as well. And sometimes lines are discontinued. Breeders usually don't announce this. . .they just stop making a line for whatever reason.
On your AK47, IIWY, I'd just buy the regs and sex them. . .honestly, its better than just sitting around waiting indefinitely for a drop.