Is it necessary to reply to a thank you message?

I'm curious, do you think it's absolutely necessary to respond to a thank you message? On one hand, it seems polite to acknowledge someone's gratitude, but on the other, sometimes life gets busy and a simple "you're welcome" might not always be feasible. What's your take on this? Do you believe there's a certain etiquette that should be followed, or is it more of a personal preference?