About Veigar CDR (is it worth keeping it or not)

How important is the cdr on him ? What i mean is ,,, is it worth it to keep the 5 % cdr rune on him ? (40 % or 45%) How important is that rune to him ? Inspiration - Cosmic insight

I mean if the 5% cdr is not that important i will change it with Inspiration - Time warp tonic Tho if its important then i wont change anything ...

my runes for him are :

Sorcery (tree 1) Arcane comet Manaflow Band Transcendence Gathering Storm _ Inspiration (tree 2) Biscuit delivery Cosmic insight