DRG lvl 78 trait question.

I'm currently lvling my DRG and I wanted to try if the lvl 78 trait that increases BoTD & LoTD to 30 sec could be used to keep your eye stacks permanently (given that you spam it every 30 seconds.)

I really doubted it would work but to my surprise it actually worked to keep my eye stacks.
But after doing it a few times i noticed that sometimes it doesn't work.

Now i'm wondering, what's causing it to fail sometimes?
Was this intended to work or not?

I'm assuming this has something to do with the server tick but whether this is supposed to work or not, this should be looked into and fixed.
It should either consistently work or not be possible at all.