Wiring LEDs in series can also save on power supply costs. Three LEDs wired in parallel set to draw 10 ma each will draw a total of 30 ma. If you have enough voltage to wire those three LEDs in series, you can run them at 10 ma and you will have a 10 ma draw for all three. If you have enough voltage to wire your LEDs in groups of three in series, then you can cut their total current draw in third.