Triangle of choice in software development

Yesterday I had a chance to listen live to the true legends of lean software development principles who visited Tallinn: Mary and Tom Poppendieck

One of the main things I remember from this 2-hours long presentation:

An ordinary triangle of choice (a client has to give up one of them - can't get all three at the same time):

Time-Money-Quality

...should rather be thought of as:

                               Time-Money-Scope

...because there is anyway so much waste in software development.

And scope cannot be given up without having trust between vendor and client.

Wise thoughts.