According to Luke 24:21 it couldn't have been 72 hours because that would have made it the fourth day.
The 72 hours is from the three days and nights of one account of the sign of Jonah. The other two accounts don't mention three days and nights. Also Like 24:46 isn't consistent with Hosea 6:2
"Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day:"
vs
"After two days will he revive us: in the third day he will raise us up, and we shall live in his sight."
Three full days
Christ was hung on Friday the 13th, which was Preparation Day before the Sabbath began. The Sabbath and Passover began Friday evening at sundown. Christ was buried at about sundown on Friday. Unleavened Bread would last from Saturday evening to Sunday evening. First Fruits was offered on Monday. The women went to the tomb Tuesday morning after the First Fruits Offering.
The 14th began on Friday at sundown. Friday evening to Saturday evening is one full day. Saturday evening to Sunday evening is two full days. Sunday evening to Monday evening is three full days. A full day is 24 hours long.
Luke 23:54
It was Preparation Day, and the Sabbath was about to begin.
Matthew 12:40
For as Jonah was three days and three nights in the belly of a huge fish, so the Son of Man will be three days and three nights in the heart of the earth.
A full LITERAL DAY is 24 hours.
Psalm 90:4
For a thousand years in your sight are like a day that has just gone by, or like a watch in the night.
2 Peter 3:8
But do not overlook this one fact, beloved, that
with the Lord one day is like a thousand years, and a thousand years like one day.
Hosea 6:2
After
two days he will revive us; on the
third day he will restore us, that we may live in his presence.
The resurrection of the elect is after two thousand years, and the third day is the end of the thousand years, and it is the resurrection of the sheep and goats.
Matthew 24
22 “If those days had not been cut short, no one would survive, but for the sake of the elect those days will be shortened. 23 At that time if anyone says to you, ‘Look, here is the Messiah!’ or, ‘There he is!’ do not believe it. 24 For false messiahs and false prophets will appear and perform great signs and wonders to deceive, if possible, even the elect. 25 See, I have told you ahead of time.
26 “So if anyone tells you, ‘There he is, out in the wilderness,’ do not go out; or, ‘Here he is, in the inner rooms,’ do not believe it. 27 For as lightning that comes from the east is visible even in the west, so will be the coming of the Son of Man. 28 Wherever there is a carcass, there the vultures will gather.
29 “Immediately after the distress of those days
“‘the sun will be darkened,
and the moon will not give its light;
the stars will fall from the sky,
and the heavenly bodies will be shaken.’
30 “Then will appear the sign of the Son of Man in heaven. And then all the peoples of the earth will mourn when they see the Son of Man coming on the clouds of heaven, with power and great glory. 31 And he will send his angels with a loud trumpet call, and
they will gather his elect from the four winds, from one end of the heavens to the other.
Matthew 25:32
All the nations will be gathered before him, and he will separate the people one from another
as a shepherd separates the sheep from the goats.
Revelation 20
4 I saw thrones on which were seated those who had been given authority to judge. And I saw the souls of those who had been beheaded because of their testimony for Jesus and because of the word of God. They had not worshiped the beast or his image and had not received his mark on their foreheads or their hands.
They came to life and reigned with Christ a thousand years. 5 (The rest of the dead did not come to life until the thousand years were ended.)
This is the first resurrection. 6 Blessed and holy are those who have part in the first resurrection. The second death has no power over them, but they will be priests of God and of Christ and will reign with him for a thousand years.