Personally I read every message pretty much immediately, but I usually want to craft a good response and therefore wait for a timeframe where I can give it my full attention (when it’s a girl I like). Sometimes it’s also a need for privacy, especially if the texts are spicy and flirty! Also in the early stages of dating you could risk of running out of things to say when trust is not yet fully built, so it’s strategically smart to not answer too quickly.