The Reference Desk/immortals

I've noticed a seeming inconsistency about the guys who basically lived forever and, though off-screen, inhabited every single century in a rather wide range. On the one hand each century page carries an (identical) notice about them living through this century (cf. e.g. 10th century). On the other hand, the immortals themselves are not put into every century's category. Jack is seemingly only in the categories for the centuries we saw him (despite being buried for about 2000 years and clearly being there). Ashildr seems to be in every century until The Woman Who Lived and then there is a curious gap between that and Face the Raven. I would be in favor of just adding all categories to them (especially to Ashildr who lived till the end of the universe), but wanted to first check if there is some clever thinking behind the current state of affairs.