Many sites don't contains the full content even if you do that. I'm not sure of how it works (does it subscribed to them all?) but https://archive.ph/ is a good way to see the content in those cases. But really, if you are regularly reading content on a site you should subscribe to support the journalists employed there.
If they had a common subscription, where you pay one reasonable fee and they divide it up according to whose articles you read, I'd subscribe to that. Since they don't, I subscribe to one paper and do workarounds on the others. I feel this is ethical because if everyone did it, with a decently random distribution, then the newspapers would survive just fine. They'd make the same overall revenue as when everyone had one newspaper, showing up at their doorstep each morning.