I sometimes use my iPad as a personal hotspot for two of my kids when we are in the car. I used to do this when they used my second iPad. They each have their own now so today I set both of their iPads up to use my data. Data usage went from 0-100 VERY fast! I looked at the account this morning and only saw about 119 MB of use for the month. They were each online for less than an hour. Then I received a message that said I have exceeded 5GB for the month and another GB has been added. I understand that there are two iPads pulling data but a single never pulled half the amount that fast! I guess they won't be using that much anymore.