If people are liking 90% of the posts on their feed, the "like" doesn't become that useful of a signal to determine what people truly like. It is being used for something else at this point. Some way of extending and re-inforcing a persons graph of friends? I'm not entirely sure.
I'm 28 and people definitely notice when you don't notice one of their posts. A like is often just an aknowledgement of "Yes, I saw this, I still follow what you're up to, we're still friends"
- have at least twice as many followers as you follow
- have at least 10% the number of followers as likes per pic
So, you could have 700 followers, but follow no more than 350 people, and must get 70 likes or more per pic. That's "success." Granted, as you get into 2,000+ followers, it can get harder to maintain the 10%.
It's amazing how mean I see girls being to my 15 year old niece on Instagram. Their little meangirl phrase is "tbh" - short for "to be honest." So they're write something nice, then "tbh" and then something mean. It goes like this, "you're a sweet girl but tbh your new backpack is kinda ratchet" or "your hair is beautiful but tbh u r slutty." Or whatever... I told my sister about this and she locked down her insta but she still gets random comments like this all the time. They all do.
Getting likes weighs on my neices 24/7. They were complaining when I took them to Star Wars that their insta photograph of them kissing yoda "only" got 15 likes.... and were considering deleting it! Because only 15 likes is about 30 too few likes.