The time of the Pennsylvania Campaign of 1777, American spies had gained far more expertise. Maybe Hale's well known death had acted as a big warning.
Spies In Philadelphia
With the Continental Army opposing the attackers rejecting in numbers, equipment and health, General Washington needed immediate, first hand knowledge of the enemy's intentions, movements and condition.
Nathan Hale's brave but reckless attempt to spy on the British was in New York City in 1776.
At the beginning of the Revolutionary War, the Americans had little practice with spying, a job already much purified in Europe.