I recently had a post make it the Explore page of many non-followers. Prior to this my average likes would be about 1.2k with ~30% engagement. The post that went viral received 6.2k (as of this writing) which is absolutely insane to me.
I used the hashtag method here posted by BrandonBrener. I feel like the method played a large part of making it to the Explore page so I felt compelled to share my experience.
My account is 2 months old with ~4k followers/followings, which convinces me that account age doesn't play a factor, but avg number of likes does (more on that later).
One important thing to note (that might throw everything off) is that my post was for an editing contest. The picture was provided by a pro photographer and I added my personal touches to it (another side note, I'm not good at editing so don't think my pic stood out ). As of this writing there are ~2000 posts. I don't think I received many likes from the other submitters, since I myself didn't want to upvote the competition.
My takeaway (which is essentially what BrandonBrener explains): most of the hashtags should have a 'small' amount of postings (<100k) but you also need your average number of likes to be the same or more than the posts in the Top section.
This wasn't my hashtag method prior to last week so now I see the difference. For the contest, I purposefully inserted hashtags that had a small number of posts and average likes. I thought I wouldn't get as many likes because my followers wouldn't see it as a 'real' post. I ran out of the 'small' hashtags and was forced to use 'large' ones (about 7). Not sure if it matters, but about 98% of the contest participants did not have average number of likes above 1k.
Anyway, long story short, my post took the usual amount of time to get to my average of 1.2k likes. However, instead of tapering off, the likes kept coming and got even more frequent than usual. Comments did not grow at the same rate, but I did read/reply to all of them which made me realize the post was on the Explore page (a non-follower specifically commented she found my post that way). I did not post another pic until 4 days later, which was around the time I noticed drop-off in activity. It was a fun and interesting time to say the least.
I've only had this one experience, but I am surprised what hashtag research can bring. You're not always going hit one out of the park, but it's worth the time/effort. I am not a customer of BrandonBerner but I will say his service should demonstrate immediate value because I basically did what he outlined here. At least until IG changes their algorithms