I do lots of testing of apps in real phones, not emulators.
The thing is that the phones must be connected to the PC all day. Because of this, phones battery get swollen and I have to buy phones regularly.
Do you know any android phone which can be connected and on all day all week without getting swollen after a time?
Must be real phones, emulators are descarted.
Phone battery can be changed though, could save you a lot of money that way. Or use fairphone, it can be easily swapped in second.