Chants - why some list 20s duration?

[Killyox]

So I've been puzzled a bit but normally chants are chanted for 6s and linger for 3s - Int etc excluded.

 

However, some chants have longer listed durations, like Fampyr's Gaze which says it gives 20s of resistance to Intellect and Peerceptions afflictions.

 

In practice, it does not. What's the purpose? Amy I missing something?

 

Can't exactly make a combo of Fampyr's Gaze -> Seven Men -> Sight of their Comrades

[thelee]

I'll be it's some weird internal implementation detail where just to fill out the ability they need to specify a duration, but then it gets overridden by the chant/linger mechanics.