You also shouldn't ask people for another request if the first one takes too long. It's in the rules.
- 6.2: Don't Be a Slavedriver
If someone kindly fulfills a request of yours, do not try to manipulate them into doing more things for you. This is a terrible act and if you do such a thing you will be punished. If you want more things that badly, then don't be lazy and try your best to learn how to obtain such a thing on your own. If you can't, then try asking about it on the forum (making sure you've searched the internet first of course). You may just find you don't need anyone to do it for you.