I've got plants in all of my tanks so they are on during the dayhome.....but I like to spend time with them when I come home after work so I've adjusted their hours to be on from about 1 to 11 pm.
i manually turn the lights on on my 3 other tanks.. the 125 is on a timer with different lighting levels.. when i am not home, the 3 tanks stay dark.. lol.. lights are for humans..not fish.. my only planted tank sits near a window, so when i am not home it just gets light from outside if there ever is.. only a couple shrimp and snails and a betta in there..
Generally, no. However, I do sometimes leave lights on for my Kapampa tank, even though the tank itself is lit up enough by daylight coming in the windows. They can become too accustomed to lights off every day and become a little shy when they're turned on and leaving lights occasionally or for a few days generally cures them of it. (So, didn't pick a poll option since it's not always one way or the other.)
I used to have all my tanks on timers, but now only about half of them still are. I ended up taking most of the small tanks off the timers as all it was doing was adding to algae growth. The show tanks that I have on the first floor of the house still run on timers.
Planted tanks, so all my lights are a on timers ... 3-10pm. This only changes on the weekend where I manually turn on the timers for most of the day so I can watch me fish.
My planted tanks are on timers 10am-8pm. My other tanks need their lights turned on manually. I usually leave their lights out, as the room gets enough ambient light.
All my tanks have plants, so I have timers that turn on the tanks from 6pm to 11pm. But my basement also has a door that is half glass, so there is some daytime light coming through. But all my tanks are far from the door so that they don't get a lot of light.