When a token goes through the process of an ICO, there are various buyers, and those buyers would then receive the tokens in their Ethereum wallets.
How are tokens distributed during an ITO (Initial Token Offering)? Does the token owner(s) send them with the transfer function, or are there other methods that spend less gas? Ideally speaking, knowing what the common practices are and the benefits to each option is what I would like to know
WHAT I KNOW / THINK ALREADY:
ITOs usually require you to send Ethereum to a specific account, and then have a mechanism of sending to coins to either the account that sent Ethereum during the ICO, or a website that gets the input of which account should receive it, with some method of verifying you're the person sending the money to them. There are probably other methods, like sending the token to an exchange and people buying directly from there.
What I am not sure of is how these ICO's send the money to the buyers. Do they send them individually using the transfer function (like the one that exists with ERC20 tokens)? What are the most common practices and their benefits?