Things are a lot more complicated that you imagine. But to address your key misconception here, the issue discussed in this article is mainly about the egg, not the uterine lining. An egg which has been out of the ovary for longer than the optimal time before fertilization, can often still be fertilized, but is past the point where it can form a viable embryo. Theoretically, the optimal condition of the uterine lining should be timed to match the optimal time for the egg to be fertilized, and thus overshooting one would also mean overshooting the other, but in reality that's not always the case (since there is quite a lot of individual variation in the timing of the various elements of the female reproductive cycle -- google "halachic infertility" for some detail on the effects of one common variation). But an embryo resulting from fertilization of a past-ripe egg will either not implant at all, or will stop dividing and die very early, no matter how perfect the uterine lining is.