That one has been kicking around for a while and
AFAIK has never been settled.
On private flights there has not previously been such a requirement so most people will be starting a fresh one.
Practically, I wonder what purpose it serves, on a private aircraft. If the pilot wants to suppress a particular flight (say an equivalent of the old chestnut of travelling to the Middle East
after you have travelled to Israel; something which most European countries dealt with by issuing a replacement passport
) then he simply won't log it.
I keep a journey log and write in there stuff like the FAA-mandated VOR check every 30 days, plus abbreviated notes showing 50hr and Annual checks. No particular reason for doing it, and it certainly doesn't live in the plane (currently).