Well if you are really technical about it and start looking at definitions; with a touch-and-go you never come to a full stop.
Therefore the flight continues.
If you do a full stop, clear teh runway and taxi back for departure you completed one and started another flight.
So, if a full stop is involved, multiple entries in the logbook.
If tgo's are involved, single entrie in the logbook.
That was how I did in my flight training !
T&G - one entry with all landings
Full stop - one entry per flight