Max run time - red LED?

I normally think of red LEDs for saving night vision; however, I understand that a red LED takes less juice to run than white. For example, would a red Infinity Ultra burn much longer than a Ultra in white? I don't have a red Ultra, can someone tell me if its bright enough in red to walk through the woods with? I'm trying to figure out if a red LED emergency flashlight will do the job and give me a longer run time. Obviously, it would be accompanied with something in white for times I need to distinguish colors. I know this is a stupid novice question, but so far I've always used tinted red lens for red light and never seriously considered an actual red LED.

Yes, a red led is quite nice for walking through very dark surroundings. The illumination isn't the greatest, but's easier on your night vision than other colors. The runtime should be longer than the Ultra, but do you really care? An Ultra has very long runtime already.

Before the Ultra there was the regular Infinity (now discontinued but you can still find them), that was about half as bright as the Ultra and had much more runtime. That's also bright enough for use in the woods. Turquoise (cyan) is supposed to be an even better color.

I think the figures are something like Ultra, 12 hours; Infinity white, 24 hours; Infinity red, 40 hours.

Red is typically the most efficient color of LED in terms of lumens/watt. It's also the lowest voltage - typically 1.5-2V whereas high-brightness green, blue, and white are typically >3.5V (not to mention violet/near-UV @ >4V). You'll find that red LED keyfob lights run substantially longer because they feature a single 2032 (225mAh) cell vs a pair of 2016 (80mAh) cells.

Nightcutter rates their 3 red LED Chartlight at 400 hours runtime. I have one, and it'll make you tired trying to run "dead" batteries down from your incandescent lights. It goes "forever".

Photon Microlights website lists the red, orange and yellow LED at 120 hours runtime using a single 2032 battery and all the other colors including white at 10-12 hours with 2 2016 batteries. I don't know how useful the light is at the end of these times or how accurate they are but it may be a good comparison for direct drive LEDs.