There are two main levers to optimise projects’ and plants’ efficiency: Planning and Operation.
Decent Planning creates considerable cost and efficiency advantages in short time. Decent Operation creates added value over long time.
The powerful lever of Planning results from small planning costs in relation to the investment sum itself. This lever, however, looses its power quickly over project time. Therefore Planning has its strongest impact at the very beginning of a project.
Example: New build of a hydro power plant
Detailed considerations of alternatives sometimes yield surprising results.
By the way: Good and early planning gives early in the project quite some certainty on costs.