Just a heads up for everyone: this test is EXTENSIVE.
There are 3 separated test. The first one runs 30 minutes, the second for an hour, and the last for 6 hours. My console is connected wirelessly via the N adapter, however I'm not experiencing any network slowdown on my main desktop (that's hard wired)--so I guess if you want to turn your console on, run the tests and come back later--you shouldn't experience any slowness on any other computers on your network.
I kind of thought it was ironic that Microsoft trusts their consoles enough to be left on for 7.5 consecutive hours.

It's cumulative. First test 30 mins. Second Test another 30 mins for a total of 1 hour. Third test 5 hours for a total of 6 hours. If you are that worried about it put a box fan next to it and watch a couple of movies