What's the deal with potentiometers/ dimmers?

My three drivers and 18 cops are wired to a single potentiometer but I'm missing something. Could someone just sum up the merits of dimming the lights? I just don't know the how's and why's of it. My rule of thumb is pour it on when it comes to lights. Thanks

If you use your lights for the entire cycle of growth then it's nice to be able to start with them dimmed and turn it up as they get bigger. It also allows you to keep your light in one spot and not have to constantly be moving it up or down. Lots of people like to dim towards the end of flowering too.

If you can't dim then it's at least nice to be able to turn some of the cobs off. No need to be blasting away when your plants are 6" tall. Just creates unnecessary heat and wastes electricity.

Makes sense Danielson. I've always wanted my light as close to the girls as possible. Nothing worse than leggy plants reaching for the light. With MH and HPS heat was the limiting factor and when I was messing with CFL's the lights were just inches away. With the COBs they say 18 inches above canopy. With a 5 foot ceiling and 10 inch pots I'll be using up more than half of my vertical limit for seedlings. I'll run it by Dan at Timber Grow Lights. I purchased the little Angelina with the COB's but Dan recommended starting without the reflectors and going closer than 18 inches and dimming down the lighting a bit. we'll see how it goes.