I believe it was me that told you that...in your thread in the member's tanks.
I told you to put your fish where they could see each other to take pictures of them...that it would deepen theri colors and make them look better.
Letting them Flare at each other everyday or every other is very good for them. It's basically exercise for fish. They are like people in that if they never exercise they get lazy, and lazy fish are easier to turn into sick fish imo.
An active fish is a healthy fish, a depressed, lazy, bored fish is not.
I let mine see each other until they get tired of it. You can tell when one of them is tired of it..they will find a spot to get where they can't see the other fish.
It's a good idea when letting them see each other that you have a plant in there where they can get away when they need to.
15-30 min is a good time frame though...if you wanted to start a daily schedule for them.
They do need some dark time, as with everything else..they need rest also. You can't get much rest when the lights are on all the time

you know. I'd say they need at elast 4-6 hours of "rest" time to keep them in optimal health.