In brief: Link juice is an informal term for the value or signals that may flow between URLs through links. It is not a directly measurable quantity or an official search-engine metric.
How I use Link juice in practice
I address Link juice from the simplest test to more expensive diagnostics. First, I try to reproduce the problem, separate a content error from a template error and find out how many URLs it affects. I deploy the fix to a small sample, check the status and internal links, and only then extend it.
What to watch out for
A technical solution should not conceal weak content. Link juice can remove an obstacle, but it will not create a reason for a person to visit or trust the page. I therefore assess a fix together with the URL’s role, internal linking and the next step.
Questions for decision-making
- What exactly does the server return, and what does a person see at the important URL?
- Is it an individual error or a pattern in a shared template?
- What is the impact on discoverability, use or conversion?
- How will we test the change before a site-wide rollout?