Search intent is the reason behind the search. Two people can type similar things and want completely different outcomes. One wants to understand a problem, another wants somebody to come and fix it. The page that matches the intent wins, even if a rival page mentions the phrase more often.
The three that matter to a trade
Someone wanting to learn types why is my flat roof leaking. They are not ready to ring anyone, and a guide is the right answer. Someone wanting a job doing types flat roof repair Wakefield, and they want a firm, a number and evidence you have done it.
The third is people looking for you by name, which is a different situation again and where reviews do most of the work.
How to check what Google thinks
Type the phrase and look at what is on page one. If it is all guides and videos, Google has judged that searchers want to learn, and a service page will struggle there. If it is a map pack and local firms, it is people wanting a job doing.
This takes thirty seconds and saves months. It is the cheapest research available and and hardly anyone does it before writing a page.
A worked example
A drainage firm writes a service page targeting why does my drain smell. It never ranks, because page one for that phrase is full of explanations, not firms.
They rewrite it as a short guide answering the question honestly, with a line at the bottom offering to come and look. It starts ranking, and it brings calls from people who read the explanation and decided the job was beyond them.