Evaluate a significant experience...

<p>For the common app question "Evaluate a significant experience, achievement, risk you have taken, or ethical dilemma you have faced and its impact on you.", is it ok for the experience/achievement to be some project you have worked on for the past three years? I was planning to base the essay on something I've worked on quite consistently over the past three years and showing how it has impacted me, but I've seen on some websites that they really want a single experience - not something which has lasted over a long period of time. Sorry if this is a silly question!</p>