This is definitely a rare exception, but at my first job, my boss's boss's boss (basically the #2 in the engineering organization, although probably only like 2/3 of it was under his purview) somehow seemed to have an unfathomable ability for knowing not only everyone under him the org tree, but details about what they were working on. I think it must have been at least 150, maybe even 200 people, and as far as I could tell he could recall every single person's name, project, and the general status of their work without needing anyone to remind him before talking with them. Maybe he did just really studiously review notes or something before any meeting or even chance of an ad hoc conversation in the halls, but I never really saw him typing at meetings or writing stuff down to keep track of later, so at the very least he'd need to have been able to retain a lot of information long enough to accurately record it later. Witnessing this firsthand for a few years was easily one of the most impressive mental feats I've ever observed.