How useful is the Smoking heart of Incense?

Im doing unwavering faith and i am a bit skeptical of this heart.

For Zarabanda and Tiento its preety clear that the time has doubled.

But in case od Debla... it seems while the cooldown is much longer, the attack time feels the same. (Tho i expect it does doube damage too?).

So is it really worth it for longer fights like Serpies and Crisanta?