We study the evolution of partial evaluators over the past fifteen years from a particular perspective: The attempt to prevent structural bounds in the original programs from imposing limits on the structure of residual programs. It will often be the case that a language allows unbounded numbers or sizes of particular features, but each program (being finite) will only have a finite number or size of these features. If the residual programs cannot overcome the bounds given in the original program, that can be seen as a weakness in the partial evaluator, as it potentially limits the effectiveness of residual programs. We show how historical developments in partial evaluators have removed inherited limits, and suggest how this principle cem be used as a guideline for further development.