imo it's much easier to buff survivability/main damage source with items than cooldown reduction
a set of flat cdr glyphs gives ~11%
not going far for examples:
Cho/Leona get already 25% with a single Glacial/Shurelia's, which is a great buff to their capability to disable while not harming their survivability at all (cho is already beefy, leona got her 6 second shield with tons of resists)
Lux with 9/0/21 masteries gets Ionian boots (sorceress+evil tome if you really want to) and forgets about cdr items at all
I prefer to think that cdr runes are far more universal than most people think. And I find survivability runes equally less universal, but that's just my playstyle.
a set of flat cdr glyphs gives ~11%
not going far for examples:
Cho/Leona get already 25% with a single Glacial/Shurelia's, which is a great buff to their capability to disable while not harming their survivability at all (cho is already beefy, leona got her 6 second shield with tons of resists)
Lux with 9/0/21 masteries gets Ionian boots (sorceress+evil tome if you really want to) and forgets about cdr items at all
I prefer to think that cdr runes are far more universal than most people think. And I find survivability runes equally less universal, but that's just my playstyle.