Leaving my T3i ON/OFF switch at ON?

Newbie question - I have been leaving the ON/OFF switch at ON all the time, since the camera turns itself off after a few minutes and I can quickly get it back awake by pressing the exposure button. But then I got thinking that this way, it does not do its sensor clean procedure at all... is that a bad thing? Should I be turning the camera hard OFF at the end of the day at least?

Thanks!

it shouldn't matter really. If your sensor is always dirty, than yes a hard off switch would be wise. Leaving the camera in on affects battery life since the camera determines when it turns off after 1 to 2 minutes vs when you hit the off switch.

aside from that, the battery is always connected to the camera so it will drain slowly over time.

At the end of a shoot or at the end of the day, maybe. Just so that things don't get accidentally activated while your camera is in your bag, etc. I think you can manually activate the sensor cleaning (not to be confused with manually cleaning the sensor) through the menus every now and then. It's more extensive than the automatic startup/shutoff cleaning.