Frédéric Dubut from Bing said on Twitter "Every time we evaluate a ranking improvement, we look at the trade-off between cost and value." He added that this discussion is not always a fun topic but it is a necessary one.
In fact, he said this is often the most overlooked piece of general search. He said "Scale and operating cost are often the most overlooked characteristics of a general web search engine."
Every time we evaluate a ranking improvement, we look at the trade-off between cost and value. This is not always the most fun discussion to have but it's just a reality when you serve billions of queries over hundreds of billions of documents.
— Frédéric Dubut (@CoperniX) December 9, 2019
When you do queries at that scale, it is a very important aspect to look at when making changes to how search works. One small change can be very costly and yet not drive that much value.
Forum discussion at Twitter.