To be more specific, there are categories of exp sharing depending on the number of people who took part in the combat, and 5 and 8 are within the same range so the exp share percentage does not change.
I'm reading the novel along with the manga right now and it's supposed to be 4 days of school and 2 days of break, which is when the majority of their dungeon stuff happens. The manga cuts out a lot of technical details and small interactions with the world, so I would recommend reading it if...
Trust this dude.
This message is brought to you by someone who is rereading instead of catching up to extend his reading time but has read beyond the point of spoilers.