Man what a shitty history lessons Guda-san had to have had in her highschool days. Because where I'm from we had to study world history seriously and it was divided in a continental way for each year. Heck if we had time we even had to learn some legends. "General culture" they said. "You'll need it" they said. In hindsight it has actually helped me to have more fun with the Fate franchise and other similar works. So hey that is nice!
Also I believe Guda is actually 17-18, even more so if you count that in Epic of Remnant a year has passed from her blood donation and employment forced abduction lol
Yes there is a non stop flow of things that happen but remember that they still have time to fill reports and lots of paper work/research/info drops to do before the next rayshift (this is seen in game with the months between singularities).
Then we have Lord El-Melloi with us who is pretty much a walking library when it comes to lots of things that are related to magecraft and heroic spirits (how can he discern the origin and purpose of other mages' craft without the appropriate historical knowledge to begin with), Moriarty (assuming his EOR has been cleared before this one and has been summoned), he is too, a walking library and also has experience as a teacher too. Guda must have realized the importance of knowledge by the end (or middle because come on!) of the singularities (which regrettably isn't the case because Guda needs to have that "self-insert" part in their character, so some common sense decisions are just ignored because not a lot of people are that much of history nerds and it also serves as a way to deliver exposition on lore and so on). With them one could get a nice express course on global history and important figures, even those that have not been summoned.
Still, I hope this manga gets picked up because the art is gorgeous and the story is one of my favorites in FGO.