Should you say you're welcome after someone says thank you?

I'm curious, do you find it necessary to respond with "you're welcome" every time someone says "thank you"? Is it a polite gesture, or is it just a habit? What about in different cultural contexts? Does the response vary depending on the level of formality or the nature of the interaction? I'm interested to hear your thoughts on whether saying "you're welcome" is truly necessary or if there are other, perhaps more subtle, ways to acknowledge someone's gratitude.