The number of 'unneccessary' ...

The number of 'unneccessary' errors that have been committed on move 41 are legion.
 Edmar Mednis

Quotes from the same author

You must be able to handle a variety of move orders during the first 5-6 moves - otherwise you'll find yourself 'tricked' time and time again.
 Edmar Mednis
Once you are in the endgame, the moment of truth has arrived... The amount of points that can be gained (and saved) by correct endgame play is enormous, yet often underestimated.
 Edmar Mednis