So at the risk of putting fuel on the fire, I will launch the hypothesis that at one point and until very recently he was sure he could release at the end of march, but then something happened. He might had a "flash" of creativity and suddenly he realised that chapter 13 would be much better if he changed or added things here and there and it would make it significantly stronger.
But to make that happened, he needed much more time.
I remember what if volume 8, and while I LOVED that what if, there is so many ways it could have been significantly better if it had more time. We could have seen more of Sterling trying to talk to Mallory and realised that she is only interested in Opehlia Now, that would have made a much more "alive" story then what we got, where Sterling just says that Mallory wants nothing to do with him. If we had seen that Sterling-Mallory discussion while Ophelia is breeding another girl and Stelring isn't aware of what is happening... Show don't tell is always more effective.
Or I remember Kevin NTR ending of chapter 12, and while it is good, it could have been significantly better if we had seen Sterling REACTS to Kevin taking both Brenna, Ophelia and Catherine. Because in the final products, we never see him learn that Ophelia got pregnant from Kevin. In this NTR ending it lacked a cuckold aspects.
More time of development on both of these would have made them significantly better. Now when I downloaded what if volume 8 and chapter 12, was I happy I got them sooner rather than later? sure... But Once I got them and I had an opportunity to play them, that "sooner" aspect is gone and now the focus is on what is NOT in the final products. Specifically the content that would have made these chapter much stronger in the long run.
This is why if WWWG got a flash of creativity recently, and he realised he can make the final products significantly better with more time, I think he should do it. I prefer a products with more content later then less content now. That said, he really needs to communicate more with his audience from now on, transparency is the key.