astrologian royal road description

so royal road a bole and you get 150% potency on the next card you use . ive notice though that this isnt strictly true when using an enhanced spear (should be minus 30% cd time) :
-lightspeed becomes a 105sec cd rather than 100sec cd
-luminiferous aether becomes a 93sec cd rather than a 90sec cd
-synastry becomes a 63sec cd rather than a 60sec cd
so on n so forth ....
i know that the extra couple of seconds barely makes a difference but i was wondering why this is ?

*typo* luminiferous aether = 93sec cd rather than 120sec cd

You're doing
t × (1 - 1/3) = t × 2/3
instead of
t × (1 - 0.3) = t × 0.7

The problem is
1/3 ≠ 0.3
2/3 ≠ 0.7


The resulting in-game durations are consistent with the descriptions of all abilities involved here.

thank you for clearing that up for me :) my shitty maths lol