Some people do it, and some people don't; Personally I never did it, but here's my lighting schedule...
48" T5HO quad 4x54w - Bulb selection is front front to back, first bulb 6500k day bulb, 2nd bulb 12,000k bright white actinic 460nm, 3rd bulb wavepoint ultra growth wave, and 4th bulb 6000k bulb.
8am the 1 & 2 bulbs come on, 10am 3 & 4 bulb come on, 2pm 1 & 2 shut off, and 4pm 3 &4 shut off. What this does is it gives me a 4 hour light burst during midday, the reason is quite simple.... Plants have 2 chlorophyll stages, chlorophyll A and chlorophyll B, each stage peaks at different wavelengths so by going with the mentioned bulbs it allows me to target the peaks for both chlorophyll stages. Here's an image showing the peaks...
Once you understand the peaks of the chlorophyll you can target them to get healthier, more lush plants... Here's a pic of the ultra growth wave bulb wavelengths...
When you compare the ultra growth wave peaks, to that of the chlorophyll stage peaks this gives you better understanding of planted aquarium light wavelengths and how to target them.
