How many iOS devices do you use for testing?

How many actual iOS devices do you use these days for testing your apps before submitting them to the App store?

Xcode builds 2 different executables (arm7 and arm64).
For several months out of each year, the most current iOS version is not the most dominant OS version.
And there are 6 different sizes of display (3.5,4,4.7,5.5,7.9 and 9.7).
That's a lot of combinations.

Do you depend on beta test people (where you can't directly debug)?

Then again, a lot of developers depend on the iOS Simulator (which runs x86-64 code) for some, many or all device variations.