Should you keep talking if they take hours to reply?

A single reply arriving four hours late tells you almost nothing. Look at the rhythm across the last several exchanges. Are they usually answering within a day, and does the content of their messages show they're still thinking about what you said? A person who is busy but interested tends to come back with something specific, a question, a reaction to a detail you gave, a joke that builds on yours. A person who has lost interest usually sends replies that close the topic, like a thumbs up, a single word, or a confirmation with no hook.

Also check whether the gaps are getting longer. Steady slowness is one thing. A conversation that went from same-day replies to two days to a week is a trend. Treat the trend as information and the individual gap as noise.

When a slow reply finally arrives, the first job is to respond to what they actually said, not to the fact that they were slow. If they asked a question, answer it directly. If they told you about their day, react to the part that had some substance. That alone shows you're engaged without any performance.

The second job is to leave a thread they can easily pull. One small question or one specific detail is enough. Avoid anything that requires a long answer to be polite, because that turns their next reply into an obligation. You want them to feel like replying is easy and mildly fun, which is most likely to happen when there's one clear thing to respond to.

Timing your reply affects how it lands. If they sent something in the afternoon, a reply that comes in the next morning reads as relaxed. A reply sent at midnight after a long gap can read as either eager or like you were waiting by the phone, depending on what it says. Match their pace roughly, but don't mirror their delay exactly, because a reply that's exactly as slow as theirs can look like a deliberate cold shoulder.

If you've sent something and heard nothing for two or three days, one follow-up is fair. Make it light and give them an easy out, something like a question about a plan or a link to something you think they'd like. If that also goes unanswered, stop sending. Two unanswered messages in a row is a clear enough answer, and a third one only moves the conversation toward something uncomfortable.