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
Smeeta kavat buff ending before timer and cut off in operator mode - PC Bugs - Warframe Forums
Heads up: 21.0.9 did NOT fix the Smeeta Charm buff not affecting the Operator : Warframe