As I've noted before, people didn't answer your first question for a reason, but one thing I forgot to point out is that you also need to give people a chance to answer the first time at all!
Occasionally, I'll see somebody ask a question, and then resend the question a short time later. You also have to take into account the time of day. There was one message I recall that was sent around 4:30pm on Tuesday, and at 10am on Wednesday, it was "Resent due to no response." Now, sure, you waited nearly 18 hours before resending, but most of that time, people were at home not checking their email, and for a big chunk of that time they were even sleeping!
I thought 90 minutes would hold up as the record, but that was mere wishful thinking. Several months ago, a new record was set. Somebody sent a question to a peer support mailing list, and then resent it a mere 27 minutes later.
That record didn't hold up for very long, however, for the same person then sent the question a third time just 17 minutes later.
Now, it'd be one thing if the mailing list promised responses within, say, 10 or 20 minutes of receipt, but this was to a peer-to-peer discussion group, and a peer-to-peer discussion group does not come with a service level agreement.
Bonus chatter: In the time between writing this article and its arrival at the head of the queue, the record has been broken. Somebody sent a question, and then sent a repeat of the message with the additional plea "Please help!" eight minutes later.