Appreciate the feedback and recommendation! You're right that explicit judgments can get stale - fortunately for our document collection the information architecture and article structures themselves are slow-changing (the answers themselves might change, but the document that answers the question probably won't for some time). We also primarily use explicit judgments to label head queries/common topics, and may augment our datasets with fresh data from time to time. The team is currently exploring augmenting these human-made datasets with automatic judgments using click models.

For realtime feedback, we've implemented (on another search product at Shopify, not the Help Center) a "near"-time feedback loop using implicit judgments to alter search results. Perhaps I'll write a post about that one soon :) . My colleague Doug talks a bit about the new systems we're building in this blog post - https://shopify.engineering/apache-beam-for-search-getting-s....