I often rely on the tethering features of my mobile phone to access the Internet while working in a cafe, a train, or an airport. It happened more than once to hit the hard quota or 8 Gigs that my LTE plans allows me per month.
I was looking for an easy way to disable the network access to unnecessary background services, and I have found TripMode. It allows to track the data usage and disable network access by service on the go.
It also comes useful at WordCamps and conferences where the wifi is very crowded and syncing large files on Dropbox is killing the fun for everybody.
Hat tip: Koolinus