During my last holiday, an overeager podcast app used my entire quota for downloading one podcast.
Now I am looking for sulutions that will help limit bandwidth usage.
Primarily I would like to monitor and limit usage by apps (getting warnings,throttling and blocking apps).
Sometimes up/down can be treaded separately (like photo backups)
I probably have a lot of apps that I can't monitor individually, I think I should be notified about those using resources, and then be able to set limits.
Would like the possibility of several different "policies", with automatic or manual selection. (I often use a mobile hotspot, so basing it on wi-fi or mobile data is not sufficient). Can be home operator, roaming status/location, Hotspot name.
Sometimes the problem is hotspot clients of my device. Some granular control would be best.
Perhaps granular control of browses - possibility to control websites, tabs perhaps by limiting heavy downloads like flash and photos.
Limit bandwidth used by ads.
On my phone I have a Data usage listing under Settings|Connections, which is somewhat useful.
Your options will vary by version of course, but my rule of thumb when roaming is to disable mobile data altogether. As an example of why, traveling to the UK from the US resulted in a two to three hundred dollar charge even with the purchase of an international roaming package. Overage charges are too ludicrous to risk so I would stick to wifi data only if at all possible.