The Long Rotation Model is most important when paddocks are going into a long rotation.
When switched ON, Pasture.io ignores satellite images during long rotations. This is best if you are keeping accurate grazing and harvest records.
When switched OFF, Pasture.io continues to consider satellite images during long rotations. This is best if grazing or harvest entries have been missed.
If grazings are missed while the Long Rotation Model is ON, Pasture.io may assume pasture has continued growing uninterrupted, which can result in paddock covers appearing higher than expected.
As a guide:
ON = best for accurate grazing/harvest records
OFF = best when grazing/harvest records have been missed
You can update this in:
Settings 
→ Model Settings
Switch the Long Rotation Model ON or OFF, then tap Save All.
Changes will take effect after the next satellite image is processed.