A rent increase can be well prepared and still be too ambitious. The practical question is whether the figure, evidence, and tenant response all point to a straightforward notice or a file that needs Defence preparation.
Evidence strength tells you whether the comparables are usable. Challenge risk tells you whether the proposed rent is likely to be questioned anyway.
That distinction matters. If the evidence is strong but the figure is still high against the market position, the next decision is whether to lower the figure or prepare the file properly for challenge.
The Defence route is the better fit when the tenant has already objected, the figure is ambitious, or you want the rent evidence and response materials organised before the pressure starts.
The checker helps you make that call early, while you can still adjust the figure or choose the stronger route deliberately.