High School Question:

When A1 is closely guarded by B1 drives downcourt and
there is a defensive shift, A1 is now closely guarded by B2.
There never was more than a 6 foot distance between A1 and B1 or B2. Does the closely guarded 5 second count continue even through the defensive shift.

If closely guarded was continued by B1 until or past the moment that B2 picked up closely guarded, then the count should have continued.

In most officials opinion just being within 6 feet is not enough; you must maintain and adjust your guarding position and not let the player get head and shoulders past you.