I don’t see this technique as necessarily eliminating the need to screen more than one embryo. You’ll want the egg to continue multiple divisions (at least into the blastocyst stage) so that you can sample some cells to determine if the alterations worked properly. Only after that would you go through with implantation.
Also, for efficiency, I think you’d want to run the DNA editing procedure against a number of fertilized eggs to ensure that enough are generated for implantation. With in vitro fertilization, typically two or more are implanted into the mother.
Still, the least expensive means of eliminating genetic defects is for the affected individual(s) to not contribute their sperm or eggs.