I've served 80 people from one batch of scrambled eggs with no problem.
Well for 20 people if they're all coming through the service line more or less at the same time, say 7am,
about 15 to 20 mins before service I would crack 18 to 24 eggs into a bowl, whip 'em up, add cream if
you want, (don't over whip, just mix well), then go ahead and cook them all at once in an 11 - 14 inch sauté
pan, just til fluffy. Then hold them in a pre-heated sterno -chaffer with a lid on it. They'll hold fine for service,
Be sure to fluff em up now and then.
If you get low (say 2/3 gone) and still have more to feed, start another batch--only takes 8 mins or less to
cook a couple dozen scrambled, and those guests who are left will appreciate the freshness of theirs. .
Conversely, if service is spread out over a few hours, you'll have to do smaller batches, but I still
see no reason you'd need to do scrambled on an individual basis.