A tracking scan tells you where a parcel has been, not whether it is late. The useful question is how long a given status normally lasts and at what point it stops being normal. These 18 guides give the plain meaning, the usual duration, the scan that should come next, and the day to open a case.
I'd Ship That includes tracking on every USPS and UPS label it prints, so the same information reaches you and the buyer without either of you refreshing a carrier page.
If the question is how long the whole shipment should take rather than what one scan means, the delivery-time guides answer that instead.