Some economy or gentle modes are designed around a particular loading arrangement. Their energy-saving behaviour may not suit the same multi-tray load as a standard fan programme.
What the observation means
The programme name describes a strategy, not a guarantee that every recipe will cook faster or identically. Residual heat, preheating instructions and the recommended shelf can all be part of that strategy. Adding a second tray may obstruct heat movement or put food outside the intended cooking zone. That is a loading question before it becomes evidence of a defective heater.
A useful next step
Read the mode-specific cooking chart rather than applying the general fan-oven advice. For a useful comparison, record the number of trays and whether the recipe requires a preheated oven. Do not repeatedly open the door to check an economy cycle, since losing heat changes the conditions it expects. Report a continuing change under the recommended loading arrangement.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.