I've been doing that for 6 years when I didn't have internet connection. I was 8 when I got a first smart device, Android tablet. One of the first things I tried was connecting to Wi-Fi of all neighbors. 2 of them had the ultra-secure password "12345678". I remember the first website I visited was Wikipedia.
However, I have tried to not spend too much data. I only watched videos in low quality (240p) and browsed the web. For downloading large files (which I considered anything above 50MB at the time) I've used public networks. Usually at the bus station or a nearby pub.
Sometime later I got access to even more Wi-Fi networks using the convenient "WPS WPA Tester" app. Like a third of all networks used one of the default PINs.