Smeeta reload buff turned my Exergis into a Supra : Warframe
On average, a Smeeta Kavat will use its resource booster Charm effect around once every 16 minutes of active gameplay time. - Page 3 - General - Warframe Forums
In case anyone was still wondering, the smeeta's buff still applies to traces : Warframe
Kavat Build – Siren Watcher
Smeeta kavat buff ending before timer and cut off in operator mode - PC Bugs - Warframe Forums