My strategy to wait until the launch of main net instead of wasting my time to working on all of testnet tasks.
The fact that if i rarely saw project dropping their coin for the test net users. I expect nothing from testnet. That's pretty much the same as when linea was only giving NFT as a reward for all of test net participants.
I expect main net is always become the key point to be qualified for airdrop.
Actually mainnet is important for them but sometimes they also reward people who do testnet. Like the sei its not yet announcing an airdrop but from what Ive see they will give some rewards to some people who did their series of testnets. But like you said, some of these testnets are not giving off airdrop and focusing on mainnet alone. The difference is they incurred funds and of course free task are also good thing but we shouldnt expect really since its a 50% chance only.