Ibid on different pages of an essay
To my knowledge, there isn't any universal set of rules for this sort of thing. Certainly citation styles differ between fields. You could obtain any widely used style guide (e.g. the Chicago Manual of Style) and follow that.

If this is an assignment for a class, you could ask your professor what she prefers; if it's a journal submission, see if they have any style guidelines; etc.

You might want to find some published material, in a similar genre to whatever you are writing, and imitate their formatting choices. For example, if you are an undergraduate mathematics student, you could look through back issues of the American Mathematical Monthly. If practices differ, then pick something which you think looks good.

Keep in mind that &quot;different pages&quot; is ambiguous. As you work on the essay, footnotes that appeared on the same page might later appear on different pages, or vice versa. Also, if you submit your work for publication, then the published version would be likely to have different pagination, and the copyeditors might edit things like &quot;Ibid.&quot; to be in their own style anyway. So I'd recommend you choose something that doesn't cause yourself a lot of tedium.