What they did
SearchPilot added the phrase 'The Best' to the beginning of title tags on a section of an editorial site's pages. They ran the change as a controlled split test, comparing the variant titles against the original control titles to isolate the traffic effect.
What they found
The change gave a statistically significant 10% uplift in organic traffic. SearchPilot estimated that rolling it out across the whole section would be worth about 11,000 extra organic sessions per month.
How much weight to give it
The 10% lift comes from a controlled, statistically significant split test, so it is a real measured outcome for this site. It shows a simple emotive word at the front of a title can move clicks and rankings enough to matter.
What it doesn't prove
It is one editorial site, and the 11,000-sessions figure is a projection of full deployment rather than something measured directly. A superlative that works for 'best of' style content will not necessarily help transactional or navigational pages.