The whole guide is more mobile search oriented, the evaluation of the page is to be completed on the mobile device, but background investigation can be done on the PC.
So the guide has spent a lot of time on mobile users' needs, but I think this part is mainly used to train assessors to understand users' search intention, the impact of geographical location on search intention, to judge whether search results meet the search intention, and to deal with some special situations, which has little to do with how SEO can improve the quality scores of pages and websites.
Here is a brief introduction to this part.
Understand query intention: understand user's query intention through query words. The correct understanding of query intention is the premise of judging whether the search results meet the needs. Sometimes the query intention is very intuitive and obvious. Sometimes you need to think about it, such as searching "weather". Most of the users want to know the temperature in recent days, whether it will rain or not, not to know the professional knowledge.
Local characteristics: including language and geographical location. Local features sometimes affect the query intent and therefore the relevance of search results. For example, users in Shanghai and Wuhan also search for "weather", and the most relevant search results should be different. In the United States, "football" refers to football, not football.