For everyday wellness we typically recommend one cube blended OR one cube steeped (3x) per day. We also have many customers dealing with specific  concerns who opt to have multiple cubes per day.
While there is no specific amount of tea plant you can have per day, one thing to consider is your personal caffeine tolerance. 1 cube has approximately 60 mg of caffeine.
If you're enjoying as a tea, You will get the majority of the caffeine in your first steeping, and only trace amounts in your second and third.
There is also an awesome caffeine regulator found in the stems called L-theanine, which is why you get the focused energy and clarity without the jitters or crash.
We are not doctors and always recommend you speak with your healthcare provider if you have any questions or concerns.