I’ve been posting 6-9 times a day on IG lately (still quality posts) and can tell you that while my likes may have decreased my reach and impressions went up a lot.
As I can speak for a friend of mine that has grown a page to 200K Followers in three months, using video and posting 6-9 times a day with powerlikes is where it’s at when you find the right niche.
Has anyone tried this yet and what were your results?
It is all about the NICHE.
Viral niches can support 6-9 posts a day, but try to do that with something more normal and you’ll see your engagement drop like a rock.
There are several posts on the topic and it seems to be a consistent story.
I sincerely doubt your friend did 0 to 200K posting healthy foods, fly-fishing or hairstyling. It is probably gaming, memes, quotes or something of that nature.
You also need to factor in the while your reach, impressions, and engagement are going to go up with this tactic, how much of this is duplicate engagement? If one person likes a single post a day as compared to that same person liking 6 posts a day that inflates your numbers drastically.
What do you guys think about Travel/Car/Luxury/Animal/Sport pages?
What are your best results?
Your sincere doubts are inappropriate my man.
It was neither gaming, memes, quotes or something of that nature but no one said something about healthy 
Is it a “viral” niche?
Definitely! Lot’s of tasty things and DIY stuff mixed with a little bit of PL and high post frequency and patience!