When you stare at the board, deciding your 1st move, what do you think about?  Do you always play the same move or do you consider your opponent and his rating, the time control of the game, what result you need for the tournament?  To expand a little bit, OTB vs CC/"turn based"  do you go for more limiting options say the choice between going into an anti-sicilian vs ML open?  Do you play the Petroff vs the expert and the Latvian vs the "D" player?  For G/15 will you essay a gambit where in a "40/2, 30/1, SD/30" you play a rock solid exchange Ruy? Change up openings because its the 10th game against the same opponent?  What advantages and disadvantages do you see to this approach?

If you "play the board and not the opponent" with the same openings regardless of non-board factors why?  What advantages do you gain, what do you lose by this steady approach?

I normally intend to play the opening that I made preparations to use.  My openings change at least once a month, so chances are, I will play a different opening against the same opponent.  I play more gambit lines in Blitz because a pawn differential is not as important as in ling games.  Let's just tell you what I played against d4 all of this year.

Nimzo/Bogo Indian

QGD

Benoni

Slav

Semi-Slav

KID

Nimzo/Bogo Indian

Budapest Gambit

Nimzo/Bogo Indian

Semi-Slav