Your strategy can work if the coin really increases after being listed on the major exchange. But that is not always happening because that will depend on the crypto market situation and that will need time before the coin price increase. If the coin price increases and then dump so hard, I am afraid that the coin is just for pump and dump and will be hard to increase even in the future.
I define a buy zone when the price is down deeper and sometimes, that can not happen in short and need to have the patience to see that time to buy. But I am too often buy new coins because I think I need more time to buy the coin at a low price.
The giveaways, airdrops and bounties are the main reason for that. I have participated in a few of them myself and I have to say even though I believed in them, I didn't had anything to go by at that point whenever they released. I always keep those tokens for a while to see if they will gain value in the long run, but they rarely ever do. This is why I believe that there is a good chance we may end up with the same thing in most releases if there are a lot of people who got the tokens "for free".
Of course people work for it, share them, get them more popular and hyped and known, they create a public awareness that the company couldn't because they couldn't afford to pay with USDT or BTC or any other top coin, and they just gave away their own created tokens which cost nothing to them. So it is understandable for those participants to sell, nothing wrong with that, it just drops the value of the token as soon as it hits the first exchange.
Sometimes, I get that free token from airdrops or giveaways but I do not hold for a long time and will sell it fast when the price start increase but later if I see they have good progress for their project, I will check and dig deeper to see if that project is worth to buy back or leave it at once. But most projects seem to lack development more after they see the price drops too deep and need a longer time to start increasing, especially if the market is in bear market conditions. After all, I get the profit when the price increase and sell it at the top.
Those participants waited for some time before they got the token after participating in the project by spreading the project to the public so it is not surprising if they sell it and seem looks dump the price to the lower price. But if the project is good enough to survive from the dump, the price will not go too far instead can sustain on some range of the price and can increase quickly.