How does an engagement group works?

So we keep seeing requests for the engagment groups on Kik and Telegram and seems like lot of people are always keep on joining in.

Those who have been part of such groups, can you please share how do they work?

Besides that what ensures success or failure of any such collaboration?

In DM groups on Instagram, the rules may vary a bit, but generally you let the group know you've posted and they will like/comment, with you having to reciprocate of course. But many people do this a tad bit differently. They will only like/comment on stuff that they find in the groups, while others will just return whatever likes/comments they get. It can be a hassle having to copy and paste the same message to potentially dozens of groups...

...so now there are groups on Telegram. Most of these are like rounds, that are set at certain time intervals, like 9 am, 3 pm, 12 am, etc. There tends to be a "rounds" chat where, a few minutes before that time, everyone drops their username and the host makes a list, saying "like recent, comment when done". If you're not done within an hour, you're said to potentially be leeching. But that varies from group to group.