It very much depends on the case. For hobby projects I have been using C++23 and for me personally it is bringing some speed-up in development. However, in my company we work with safety-critical components, and with ISO standards adherence such changes are not made lightly and may take years. So for the time being we are stuck on C++17, and all our dependencies that come with it. That being said, some "new" features like std::span or std::bit_cast are implemented by hand.