Cooldown is 90sec by default, it fires 5 shots per barrage and at vet2 gets standard arty -40% cooldown.
-40% colldown is anything but "standard"...
ML-20 152mm Gun-Howitzer -25% barrage recharge
B-4 203mm Howitzer -25% barrage recharge
10.5cm leFH 18 Artillery -25% barrage recharge
M7B1 'Priest' Howitzer Motor Carriage -30% ability recharge time
To feel like it has no cooldown, it would have to fire 1 shot every 10 seconds, so I wouldn't be so sure about that
...
Depends on what barrage one is using, if ones use normal barrage there is around 26 sec between last shot (vet2) fired and next barrage.
If one uses "creeping barrage" for 50 MU the weapon is ready to fire almost at the time the previous barrage ends, so Stormless might have been referring to "creeping barrage"
It also doesn't get +2 shells static arty gets and even priest fires 7 shots on same cooldown, but with much better range and AoE.
The only static arty that get +2 shot is the ML-20 and that is instead of vet 1 ability...The priest is also much more expensive...
Sexton on its own is rather bad but used with the Concentration Barrage (15 munition) valentine ability has very long range.