How many hashtags should I use in order to get the most engagement rate. I make this comment, assuming that Instagram might your consider somehow quite spammy, if you use 30 hashtags and “decrease” its valuation.
Some say that the better use of hashtags is 5 or 6 -> https://louisem.com/7198/how-to-use-hashtags-on-instagram
By using Hashtags you can make your post more attractive and hashtags help you to notify your special word in a more determinable way. (#)
Normally you can use the 10-15 Hashtags but don’t use more than 30 hashtags, in the post and For the normal story, you shouldn’t use more than 10 hashtags.
Thanks for the response BrooksFunk!
Anyway, my doubt is about the relation between HT number in a post and engagement rates. Do you know something about it?
I use 10 groups of 30 hashtags. In total 300 different hashtags from my niche. I use them in order from 1 group to 10 and back to first one. So each post have 30 different hashtags.
I’m new to IG so I might be wrong but if IG let me use 30 # than why would I limit myself? The only thing bad I read about using 30 # is because they look spamy - I don’t think that 1% real followers on my accounts would care about that 
I fill my hashtags to the maximum every time. I just feel it’s better to open 30 potential doors (hashtags) for people to see my content rather than say 5 doors.
I’ve tested it before with 5 super popular tags or 5 researched tags versus 30 tags with a mix of everything and the 30 tags seems to get the most follows and likes/comments every time.