I think it's USAFA that asks for this, but good to do this with your "master" resume (of everything possible, from which you pull and customized all other resumes and honors/leadership/achievement lists): assign the amount of time and dates for all activities. Anyone reading your resume could basically tell where you are, nearly 24/7 and what you are doing. That is not the only measure, but time spent is one good measure of how involved, over how long and leadership/achievements. Think BME - beginning, middle, end. What was your goal, what did you do/how did you do it, and what was the result?
Another way to think of this is if I ask,
I don't have time to read your resume. I've read 100 other applications and my eyes (and brain) are glazing over.
So briefly tell me the 5 most important things about you, and inspire me.