ECs and time

Hi, I was wondering - for mostly top universities, does it matter how long you’ve participated in those ECs? What if, majority of my majority accomplishments, happened only a few months before I sent off my college application? I’ve seen a lot of people having participated in those ECs for years. If it is, the fact that I was sick most of my teenage years, can that be excused?
Sorry if that was awfully worded, I am quiet tired.

bump