My quote was from ICAO Annex 1.
And under the UK system you are definitely not allowed to carry anybody either.
For a CPL its an experience requirement that is obtained prior to starting a CPL Course so it doesn't matter a damn what any school thinks about it. There is no requirement for it to be solo. You only need log book evidence for licence issue.
nteresting that you interpret a "day" as a 24hr period.
Think of the X- ctry that starts late in the day, something goes wrong, aircraft or weather and the 3rd leg can't be made till the next day. If the aircraft is back within 24 hours the UK CAA accept its still in a day and the same trip.
note from LASORS talks about "two intermediate aerodromes", suggesting that an A-B-C flight is not acceptable
It is the most common option, but A-B C is quite acceptable.