That is entirely up to you.
I prefer a minimum of 2 devices. One for the OS and Apps that need to be reinstalled when the OS gets reinstalled and the other for apps that will work without needing to be reinstalled; Such as Steam games. I keep my library on a separate drive then the OS. If I need to reinstall the OS, I just link the library after I reinstall the Steam client. {Steam client needs to be installed with the OS install so it's on C:}
That is entirely up to you.
I prefer a minimum of 2 devices. One for the OS and Apps that need to be reinstalled when the OS gets reinstalled and the other for apps that will work without needing to be reinstalled; Such as Steam games. I keep my library on a separate drive then the OS. If I need to reinstall the OS, I just link the library after I reinstall the Steam client. {Steam client needs to be installed with the OS install so it's on C:}