Since most bands you've heard of have already hit their peak, I'm inclined to be prejudiced against bands' most recent albums. This bias remains, despite my awareness of the possibly of exceptions.
When checking out a band with a large discography, I always start within their first few releases. The reason is that bands with many albums tend to be at their best during the early or middle era.
A related bias lies in the view that the sub-genres of metal reached their peaks well over a decade ago. Because of this, a newer band will more likely be a waste of time--says the bias--than a band from the 80s or 90s. This is a real issue, because the bias manifests itself as a prejudice against newer bands.