3 things:

• Assume a certain incertain based on distance to the target, to avoid recompute paths every turn when the target is far way and moving.
• Handle cases where the target is unreachable to the long-range pathfinder and we would be recomputing every turn.
• If we went straight, assume we don't need to recompute a path.

These together mean entities recompute paths far less often.

Order units somewhere impassable: notice paths don't get recomputed every turn.
Order an infantry unit to guard a cavalry and move the cavalry away - notice how the path doesn't get recomputed after a while.