So I just had a look at the update, and I count 30 Android devices and 26 iOS devices. Obviously there's plenty of doubled-up devices in the iOS cupboard, but it looks like a couple of the Android devices are doubled-up as well.

My own app is tested on 4 devices (three phones and a tablet) and 2 of those devices were given to me by friends. I'm certainly not a top tier developer, but looking at a single developer who tests on 400 devices and saying "this is what developing for Android is like" is simply factually incorrect. Especially when another top tier developer is only testing on 30 devices. And ESPECIALLY when the vast majority of "normal" Android developers test on a handful of devices only.

Maybe it's a competitive advantage to test on 400 devices. But it's not REQUIRED, and it's certainly not NORMAL.

How many devices do the Instagram developers use? Since there's only one guy developing the Android version it's hard to imagine that he uses 400 devices. If he did, there would be no time for writing code.