Structural modes are editorial aids
The bundled article and letter templates are starting structures, not authoritative
journal schemas or proof that a publication accepts that content type today.
Use the current journal's guide to select a submission format. The old generic
portfolio-article/portfolio-letter preflight profiles have been removed.
For a full research article, an abstract plus Introduction/Results/Discussion/Methods can help organise the evidence. For a concise narrative, a connected sequence of claims may work better. Main Nature Articles use a referenced summary paragraph; other journals can require an unreferenced abstract. Choose from the verified journal contract, not from the perceived prestige or length of the paper.
Keep section headings when they help readers and the format permits them. Choose
one term consistently for the opening. Do not add an artificial 'Summary paragraph'
heading to the final submission merely to satisfy this skill's optional checker;
use a separate text extract with --opening-only instead.
The useful questions are: what does the opening need to communicate, what evidence supports each section, what order makes the argument clear, and what end matter is actually applicable? The title and word limits, number of figures, heading policy, and required declarations come from dated journal-specific evidence.
See journal calibration for the actual length-check profiles and their deliberately limited scope.