Recently began to notice a lot of closed groups in Instagram (mostly they are closed), from which 100, well a maximum of 200 posts and the number of subscribers from 1.5 million or more. Please share your opinions with what can be related to such success? What are the model on this quick and effective to attract subscribers?
Here is an example of the group - https://www.instagram.com/wildphysics/?hl=ru
There are other subjects.
Know the different ways of promotion groups, but then can't track patterns. They even have many posts, no signatures, no herzegov.