Less sun usually means less evaporation
Shade reduces the energy driving water loss from leaves and soil. A plant in shade often has a longer watering gap than the same plant in full sun.
Not all shade is equally damp
A wall can create a dry rain shadow, and tree roots can take up water before your new planting gets much. Feel the soil rather than assuming the word shade solves the question.
Use the shade setting as a nudge
The app treats shade as one adjustment alongside rain, temperature, humidity, planting type, and your last watering. It should guide your check, not replace it.