Iteration does not guarantee good design but lack of iteration most definitely results in bad design.

Onur Cobanli ཡིས་འགྲེལ་བཤད་བརྗོད་པ།
You must most definitely try different variants of your design, especially if it is a product, interface, service or experience that will affect millions. It is always better to try to improve your design, you must iterate, you must think always, how you can make it better; even if you have great design, iteration could lead to a superior design. Iteration is one major way a design can be made better; designs can be improved by many means, such as having better observations, having better control and access to knowledge and materials, and being in a better mood when designing, so these all help, but as you realize, these are mostly external; i.e. you may not have access to better materials, you may not have opportunity to make more observations, but you will most likely have control over your subjective time; iteration is more an internal thing than external, it is something you can definitely control; you should iterate as much as it is economically feasible to do so, with everything else constant, the iteration will help you make better, superior designs.