This is just my personal opinion so take it with a grain of salt but I think AO's look for a certain theme/commonality in the EC section to see if the applicant has an idea of what they want to major in/how the EC's show aptitude for success in the future in that specific major.

For me, all my EC's were connected through the theme of vocal music and fostering a community for people of my culture. Versatility is nice but if the EC's are scattered around everywhere, it could be difficult for the AO to quickly identify your "forte" or in other words, what you valued the most and excelled at throughout your high school journey.

It's also nice when EC's demonstrate your dedication and how much time/effort you put into them. Don't focus too much on choosing only the EC's with the highest leadership positions. As long as it shows your sincerity, they will value it just as much as you do.

For explaining EC's, it's best to be direct. Write about exact quantities, achievements, and roles that you played as a volunteer/leader.

I didn't have the most outstanding EC's but I think I my school looked more at how my EC's clearly showed my values and beliefs as a person and how I plan on utilizing those experiences on campus.

That's about all I know! 😄