The point of iteration is not typically to find the best implementation for a given algorithm, it's to find the best algorithm for solving a given problem.
I can see the argument that Rust encourages by its design a clean implementation to any given algorithm. But no language's design can guide you to finding a good algorithm for solving a given problem - you often need to quickly try out many different algorithms and see which works best for your constraints.
I don't think iteration is usually about testing different algorithms – it's much more about finding out what the problem is in the first place (that is, attaining a good enough understanding of the problem to solve it), and secondarily about finding out a solution to the problem that satisfies any relevant boundary conditions.
I can see the argument that Rust encourages by its design a clean implementation to any given algorithm. But no language's design can guide you to finding a good algorithm for solving a given problem - you often need to quickly try out many different algorithms and see which works best for your constraints.