That's super annoying. In Firefox on Android you can disable the browser from downloading images, maybe there's something similar on iOS browsers? There's also [https://play.google.com/store/apps/details?id=com.onavo.android.onavoics&hl=en](Onavo) on Android, which acts as a VPN through their servers where they'll compress a bunch of stuff, and cache a bunch of stuff. It hasn't saved me "5 times the data" that they claim, but it's definitely helping.
Opera's off road features are the best in that category