In marketing and advertising, a mental model that gets referenced quite regularly is what's called the Project Management Triangle, or the "Iron Triangle". This is also one of the most polarising concepts I have seen, so remember to use it wisely.

The Project Management Triangle is essentially a positive trilemma, where there are three favourable options, but only two can be achieved at the expense of the other.

Traditionally, this was applied to the variables of Time, Cost and Scope. More recently however, scope is often interchanged with a sub variable; there is a tendency to utilise Quality, Product, Goals or Deliverables (with Quality utilised most often).