All depends on how busy people are, the time of day the question was posted, and the day of the week. I guess most people on here visit daily either to scan new posts (like me), or review just the sections they are interested in.
So if you post a question in the morning, it should receive a response by the end of the day. If you post a question in the evening, it may receive a response within hours, or it could be 24hrs - the next evening. It could take longer over a weekend - people do have lifes off the forum.
Have to say it does make me laugh when a question is posted, and then an hour later they are re-posting asking if anyone is bothering to read/answer the question - as though they expect people to be sat waiting for questions to be submitted.