Anon-metal usually forms 2 covalent bonds in its compounds. how many electrons will it take in its valence shell？

In covalent bonds, non-metals share electrons to attain full valence shells.

This non-metal usually forms 2 covalent bonds. This leads me to believe that it has 6 valence electrons to begin with and will take 2 more, one from each bonds. Such that it ends with a full valence shell of 8 electrons.