IIRC, commercial cinema is actually 24 frames per second, not 30. (This used to cause quite a few problems when computer screens were seen in movies, in terms of flicker on the computer monitor. Reseting the monitor refresh rate to a multiple of 24 was the simplest solution.)

Regarding the human eye noticing refresh... I used to earn a living writing the graphics software for large-scale military & commercial simulators; studies there showed that its not just the rate at which your graphics are re-rendered that's important, its the screen refresh rate too.

As an example, let's assume that you can generate a new frame 30 times a second; if your monitor refreshes at 30 hz, then the display will look pretty smooth. With the same 30 frames per second being generated, if your monitor refreshes at 60 hz, then the scene is actually noticeably more "jumpy". So, if you could have your frames being generated at N x your monitor's refresh rate, for positive integral values of N, that was optimal.

Of course, the above was a few years ago ... who knows what new ideas or 'facts' have come to light since then. ;-)

Regards,
Gordon