How long should I wait after being left on read?
For a friend, a day or two. For a dating match, about a day. For work, two or three working days. Shorten it if there is a real deadline, like a plan tonight.
Is it rude to leave someone on read?
Usually it is just life. Most people read and mean to reply later. Some open every message straight away to clear the notification and reply in batches in the evening. It becomes rude when it is a pattern with things that clearly needed an answer.
What if a match leaves me on read?
Send one new, light message after a day. If that is read and ignored too, move on. A match who wants to talk will talk. Chasing past that point rarely changes the outcome. If they reappear a week later with an apology, you can decide then whether you are still interested.
Should I double text?
Once, yes. A double text with something new to say is normal. Repeating the same question or adding a third message is where it starts to read as pressure. If the second message gets no reply either, stop. The next move is theirs.