Do you even know what three days and three nights means?
To a first century Jew it is a idiomatic expression meaning 3 days. Jews counted any part of a day as the whole day. Look up inclusive reckoning.
To a westerner in 21st century, it means 72 hours.
We must take the meaning in the first century, not 21st.
Yes, any part of a day was counted as a day, UNLESS is is more particularly specified. Three days AND three nights means . . . . three days AND three nights.