First of all it depends on what u plan to major in or what field ur going into. For example, that phrase is correct in most cases. You don’t want to fill up all 10 slots for ECs if half of those are just members or you made no impact in them. Only list the Extracurriculars you either had a leadership position or significant impact. Of course you would like some of your ECs to be consistent throughout high school but don’t worry if you just started it in junior year. Just try to make a big impact. Additionally remember that ECs include internships, clubs, nonprofits, volunteering, or anything in general you spent your time in. I feel like 4 is not enough and you should aim for at least 6-8 to show colleges your interest and passion. Also make sure that there is a consistent theme throughout your college application.
i don’t think it’s bad at all to have started activities in quarantine! just make sure that you genuinely enjoy and are passionate about them. i know everyone says that, but it’s the truth. it’s very impressive that you are yearbook editor as a junior! keep at it, and if writing is a passion of yours, look for some online publications that take submissions too. and don’t spend too much time on this site, there are a lot of people here who can be very mean and toxic! best of luck to you! you got this!
Your pattern is likely the most common among students who engage is ECs. CC is strange in that there are an inordinate number of students who have multiple interests or ECs in which they have been engaged for their entire high school period. Having one for all high school, a couple from Sophomore year, and a few which you picked up during quarantine sounds pretty normal for a kid who is active outside the classroom.