Is it Necessary to Follow Chord Instruction Above Grand Staff (Piano)?

Question

From old posts on this website, I understand that for piano sheet music, the letters above the grand staff represent chords to be played— and these chords can be played instead of the single notes on the staff. But is it necessary to follow these chord instructions above the staff, or can I simply play the notes on the staff?

I am attaching an example of this from "We Wish You a Merry Christmas," in which, for example, instructions for an E7 chord are written above a single E note for the left hand. In this situation, can I simply play the single E note, or do I have to play the E7 chord instead?

Answer 1

You don't have to do either. If you wished to play the piece verbatim, then you'd play what's written on the stave. Exactly. The 'E7' is there to guide another muso, usually a guitar player, as to which chord is appropriate for that part of that bar. The notes constituting the E7 chord are there being played by the right hand anyway, with the usual root in the bass. So, it's an entity in itself, although if you wished, you could add extra notes - choose from E, G#, B and/or D, in the left hand.

Answer 2

You can just play the notes on the grand staff.

To be exact: the notes on the staff are a specific arrangement of the chord symbols above the singing line. The chord symbols are there as information to the player who wants to change (simplify for example) the proposed arrangement or wants to play the song on a different instrument (a guitar for example).