The real cost is agreement, not writing
Writing the sentences is not the bottleneck. Keeping every restatement of a number consistent across a long document is. A report may mention the same result in the abstract, the results section, a table, and a figure legend, and all four must match. This is a checking problem more than a writing problem, and checking problems are what automation handles well.
What the draft looks like
Suppose the analysis produces a table showing that a treatment reduced a symptom score by a certain amount with a stated range of uncertainty. A drafting tool can generate the sentence describing that result, place it in the results section, insert the matching figure reference, and flag that the same result appears in the summary and must be worded consistently there. The medical writer then decides whether the sentence overstates the finding, whether the uncertainty deserves more emphasis, and whether the result belongs in the summary at all. The tool has removed the transcription work; the judgement about meaning is untouched.
Templates help and constrain
Reports and submission documents follow fixed structures, which is why drafting tools work well on them. The same fixed structure means a draft can look complete while a section is substantively wrong. Completeness of form is not evidence of correctness.