There is so much truth to this... seriously if things are going to get cancelled, they move it to this time slot or to Sunday's at 10. It's how you ditch a show, and blaim it on ratings not network or advertiser lack of interest.
"Unlike the 8 o’clock time slot which seems to allow for the success of multiple prime-time television shows, the 10 o’clock time slot on Tuesday nights seems to be a “death slot” -– meaning it is mutual-assured-destruction (M.A.D.) for just about any show unlucky enough to be broadcast at that time.
Saturday nights are generally known as “dead” nights, and prime-time television series have not been programmed on Saturday nights since the late 1990s. Alas, the weekend curse seems to have spread to Friday nights, and now it is notoriously known as a “TV show killer” night. Only shows sent to certain death are broadcast on Friday nights. Good examples are “Smallville,” “Supernatural” and “Medium,” which are all in the midst of what is thought to be their final seasons. Fridays are also good for shows with an uncertain fan base such as “The Good Guys” –- it allows it time to develop an audience kind of under the radar. Fridays also used to be known as “sci-fi” Fridays which changed to Syfy Fridays after the network changed its name." See the rest HERE