I never had the issue with patchiness. My beard grew in full right away. I think if you're otherwise tight and put-together, the contrast of the patchy face makes you stand out. In terms of cleaning up certain areas...I would keep the mustache clean. If you see that little area on Keanu's face where the beard is kind of growing towards his cheekbone, I would trim that off. Otherwise, leave it alone if you don't mind waiting until the thin areas grow in.
"The best kind of pride is that which compels a man to do his best when no one is watching."