Proverb, quote or phrase which convey that the approach, ideas that are meant to improve the system or process are the onces which fail them

Proverb, quote or phrase which convey that the processes (or structures or ideas) which are supposed to bring in efficiency, enhance the gaps and increases in-efficiencies are the reason for its decline.

Explanation with example"
Hiring big external agencies to define the efficient way to improve are the once which do not understand the system and do all sorts of trial and error methods to innovate the process for years and not only waste company resources but are paid ton of money, to fix what can be done internally.