Are You Too Biased to Poskan for Yourself?

It’s been a while since I summarized my psak shiur, but I’ll try to catch up. In the previous post on this topic, we began dealing with the issue of poskaning for one’s self – when is one qualified, are there different standards for ruling for one’s self than there are for others, etc. The second question is whether even an unquestionably qualified posek should or must refrain from ruling for himself due to bias. In the past, when dealing with the benefits of having a Rebbe (here), we noted that practically it is often good to have an outsiders perspective, both to ensure that you are not too lenient and to ensure you are not to stringent on yourself. Is that a Halachic requirement?