The cycle time for PI Temeperature Control

Hello fellow control engineering specialists!

I am currently working on a project for developing a solid electrolyte hydrogen gas sensor. Solid electrolyte sensors have an operating temperature to be maintained for their required ionic conductivity as per the measuring principle. And such a sensor shows a great amount of fluctuations in presence of a PI temperature control. In one of the important literature it is indicated that such fluctuations could be eliminated if we half the cycle time of the controller. My question is regarding this particular parameter of cycle time? What is a cycle time of a PI controller and how could it be mathematically stated.

Thanks in advance for your insights! Cheers Pramit