This is because stories were traditionally told using the past tense. This made the narrator sound as if they were narrating events from a distance, instead of being 'present' amongst the action.

Male in hi-viz jacket: Past, present and future tenses are important because we may use the term say 'there is wear' in a component. So we'll have a look maybe it might last a bit longer so we'll ...

One’s tense will vary depending on what one is trying to convey within their paper or section of their paper. For example, the tense may change between the methods section and the discussion section.