I thought that you can only receive 20 requests per day and send 30. I've been sending requests out to only 20 when I need 15 and 25 when I need 20. If I'm coming up short, I can still send a few more. I haven't had a problem. I worry that if you send out to all your neighbors, it takes days for them all to receive the request and I'd rather make sure my requests go to active, reliable neighbors. Maybe that's why we sometimes get a 4 day old request? I don't know when the requests expire, but also worry that someone will send what I needed days ago, messing up what I need now.