Sweet allows for full 4G LTE data usage up to 18 GB of usage. All plans slow to 128 KBPS at 18 GB of usage, with a hard cap at 22 GB that restricts data usage beyond that point.
To keep your data usage low to keep from slow data and from hitting your data cap, here are a few suggestions:
For all devices:
While at home or elsewhere, it is recommended that WiFi is used instead of data.
Restrict Background Data Usage
Some use data while you use other apps to update content. To turn it off, tap Network & Internet > Data Usage > Mobile data usage and select "Turn off background data usage".
Turn Off Wi-Fi Assist
Wi-Fi Assist turns cellular data on when Wi-Fi connectivity is poor. By turning it off, you can keep from using data.
Turn Off Background App Refresh
When Background App Refresh is turned on, it uses data to refresh app content. Set it to "Off" or "Wi-Fi" to keep from using data to refresh app content.
Turn Off Cellular Data for Automatic iTunes and App Store Downloads
Cellular data can be used to automatically update iTunes and App Store downloads. Turn it off for App Downloads and App Updates to conserve data.