Sorry for late response . I think , IBN 5100 is really huge indicator how far Okabe is from Betaattractor field . With each Dmail he sends world becomes more and more different from original state , gap between world ' s divergence number and desired 1 % becomes bigger as well . Since IBN is a key to attractor field , the world is moving this item further and further away from Okabe ' s reach to make attractor field logically harder to achieve since world as a whole is much more different and returning to it ' s original state must be more difficult too and requires more actions . It ' s like world ' s shield , that safes him from changing to extremely different worldlines . World ' s inertia . Same applies to Mayuri ' s death . Every time Okabe changes world even more , she is dying earlier . But her death is quite strange , tbh . It ' s weak explanation , though . I guess , IBN is moving farther and farther away just for narrative ' s sake . And I ' m ok , if someone broke fate , cause someone helped him . I don ' t like , that it happens , when he basically gave up and was never going to try this again . But I guess , you already got my point . PS It ' s Russian . Some people can easily tell what my first language is , when they see my commentaries . haha