Tom,

Assuming two current etc etc etc pilots, flying in VFR conditions, neither
under the hood, both qualified to act as PIC...

One (and only one pilot) chooses to ACT as PIC.

The pilot manipulating the controls logs the time.

Example 1: Pilot A is PIC, pilot B flies the entire flight. Pilot A logs
nothing, Pilot B logs it all.

Example 2: Pilot A is PIC, they share the flying time - both pilots log half
the time.

Hilton