Testnet airdrop meant if the developers are giving you reward to try their testnet and check how reliable their network is. There's no guarantee if you can get the reward from using their testnet. The developers has been creating a pool that will be divided among some lucky testers. that means only some people can win the reward while the rest got nothing. If you are lucky enough and you can get reward from what you have been doing before. It's random reward. that's why it's called airdrop.
It is not a random reward, but rather, project developers will only give rewards to those who have contributed the most, the most useful ideas to the project. That means you have to work hard and give your best to get the reward, not you just sign up and sit there waiting for them to give you the reward. Rewards only for those who deserve it not for spammers like airdrop. But not every project will give out rewards after the testnet program ends, the testnet is voluntary, they will not notify in advance that there will be rewards for participants.
It is only notified after the end of the program.
