When i was first participating airdrop, that was last quarter of 2017, it was just an airdrop: fillup the form, do some required task, join social medias, submit, then thats it. I can say that those days, airdrops are good, though rewards wil be sent for a months. Nowadays, most airdrops depends on referals, so your reward (in tokens) depends on how many referals you earned. So i joined bounty to earn more tokens.