How many times can we call getIdTokenResult(true) per day?

[gOzaru]

Hello.
I want to use claims which are registered inside token through Cloud Function in my client app.
Until now I haven't found any of documentation which stated that there is a limit which we can call of getIdTokenResult(true). If that is true, if I call it every 12 minutes to check whether the User has signed in on new device, will it cause me a high surge of bill in the end of month if my total users are 1,000,000?
[1 User calls 120 times per day]

Please help me.
I need to prevent sudden surge of bills.