I think the answer could be:
"Video games these days often contain weekly challenges." And all the clues pertain to Fortnite: Battle Royale which includes weekly challenges.
This fraction reduces to 5/31, which could read as May 31st - the day in 2018 that Epic Games introduced "Fortnite Week 5 Challenges" to Fortnite:Battle Royale.
Jumping spiders in the Holy See
It has been said that the ingame map is "4x the size of Vatican City" (Vatican City is The Holy See). I'm not a Fortnite player myself, but I have seen that Vatican City, Spiders, and Spiderman all feature in gamer streams, not sure if these are mods or not.
From a battle entertainer in the royale court
A reference to Battle Royale
less than weekly
A "fortnight" is 14 days, which is more than a week, and so occurs less frequently.