Every damn time. IMO, it's not really free if it requires a payment method; free trials should automatically end when the time is up instead of making you the one responsible for canceling to avoid being charged.
In Europe you can probably use Revolut, they let you generate single-use cards.
Please note however that websites can tell it's a single-use card and refuse to accept it. Most recently Amazon and their related services (Twitch etc.) started refusing them.