Generate the formal Section 13 notice pack once the rent figure, evidence, and service plan make sense together. The checker helps you get to that point before the form is created.
The Standard Section 13 pack is for landlords who have a supportable figure and want the notice, market justification, and service record to stay aligned.
Run the checker first, settle the figure, then generate the pack once the evidence and the proposed rent are pointing in the same direction.
If the rent is still moving, the comparables have not been reviewed, or challenge risk is already obvious, serving the notice can put you on the back foot.
The cleaner pattern is simple: run the checker, read the supportable range, decide whether the case is Standard or Defence, and then generate the pack that fits.