TIL you can have up to 89,164% Cooldown Reduction on your ultimate in a Summoner's Rift game. This means that you can use you R almost twice as often as in URF. :
A Beginner's Guide to League of Legends Situational Items - Mobalytics
Ability Haste and Cooldown Reduction - What's The Difference? -
Wild Rift Patch Notes 1.1
League of Legends: Patch 13.6 Nerfs Navori Quickblades Cooldown Reduction, Improves Nashor's Tooth