Hi Mate,
Good question - I presumably it probably was preferable because it was an even figure - remembering there's multiple market with different session times.
My understanding on the ASX being a 6hr live trading session is that depending on the software you use - you can program when a candle starts and ends and also the timezone For e.g. trading view which is better to use on my handheld devices 4hrly defaults 0800-1200 1200-1600 perth time.
In saying that i don't use 4hrly or 3hrly for candle stick patterns.
IMO hourly, daily, weekly are the 3 key timing intervals for candle stick patterns unless you're day trading forex/etfs etc where 5/15mins can be useful.
I use 4hrly by default as it's more common across basic chart platforms than 3hrly. But it's never for candle patterns - its more for the MACD/RSI?stochastics/EMA etc - as you get a longer term view than the people trading hourlys so are less reactive but conversely can recognize entries and exits earlier than someone trading the daily. In that instance the 3/4 doesn't change the analysis that much - but call out for 3hrly if trading only the asx
https://forums.babypips.com/t/candle-close-times/80606
here's a post with someone asking the same question with some more info in there.
SF2TH
(20min delay)