When was the last time you went back through your “early research” and checked your citations and determined where the information was actually located? Sometimes early in our research, the rush to discover, and possibly because our experience and skill level still needs to be developed, conclusions are made that are not quite correct and sources are used that are not as reliable as others.
Cleaning up old citations for me has been a great brick wall breaker and “leads I never followed up on” finder. Sometimes that’s all it takes to get my research started again.