[klaustopher]

What I have done in the past:

Scroll down a couple of days/pages/whatever and then use Ctrl+F. It‘s annoying as hell, but that usually works as most pages just add stuff at the bottom and don‘t unload the previous content on top

[mijoharas]

As mentioned above, there are some sites that page out the content that is no longer in the viewport after you've gone suitably far from it.

I still remember my consternation when I first noticed this, and it was because I tried exactly what you had suggested, but a previous match further up the page disappeared upon subsequent CTRL+F-ing.