How would I know it ever occurred after a single generation, based your own statement? But I dont think so. Nor would it be necessary.
It sounded like you're challenging the understood reality that speciation events take many generations. That's just how I perceived your comments. Its fine if that's not what you meant to do.
There really are just lots and lots of challenges, scientifically with YECism. And everyone knows it. Oodles of challenges. A lot of things that logically don't appear to add up.
And, simultaneously, the context of the Bible also indicates that Genesis isn't about science, nor does it teach science, nor does it teach things such as the age of the earth. The context is ancient near eastern. Genesis describes ancient near east cosmology. And it's about temple construction. See Isaiah 66:1-2 for a better understanding of God's rest on the 7th day.
Isaiah 66:1-2
[1] Thus says the Lord: Heaven is my throne, and the earth is my footstool; so what kind of house could you build for me, what sort of place for me to rest? [2] All these things my hand has made, so all these things are mine, says the Lord.
It's about God building His temple. Then when the temple is complete, that is the cosmos, God rests on the throne.
And that's what God does in every other temple in the old testament. God does that with the tabernacle. God does it with solomons temple. God does it with ezekiels temple etc. see Ezekiel chapter 43 for example. When the temple is constructed, God dwells among His people.
“But will God indeed dwell on the earth? Even heaven and the highest heaven cannot contain you, much less this house that I have built!
Hear the plea of your servant and of your people Israel when they pray toward this place; O hear in heaven your dwelling place; hear and forgive.
1 King 8:27
So Solomon held the feast at that time, and all Israel with him, a great assembly, from Lebo-hamath to the Brook of Egypt, before the Lord our God, seven days.
1 Kings 8:65
And you shall not go outside the entrance of the tent of meeting for seven days, until the days of your ordination are completed, for it will take seven days to ordain you.
Leviticus 8:33
temple priest ordination in 7 days.
And in the eleventh year, in the month of Bul, which is the eighth month, the house was finished in all its parts, and according to all its specifications. He was seven years in building it.
1 Kings 6:38
The Temple constructed in 7 years.
And all the men of Israel assembled to King Solomon at the feast in the month Ethanim, which is the seventh month.
1 Kings 8:2
“But will God indeed dwell on the earth? Even heaven and the highest heaven cannot contain you, much less this house that I have built!
Hear the plea of your servant and of your people Israel when they pray toward this place; O hear in heaven your dwelling place; hear and forgive.
1 King 8:27
Inauguation feast on the 7th month.
So Solomon held the feast at that time, and all Israel with him, a great assembly, from Lebo-hamath to the Brook of Egypt, before the Lord our God, seven days.
1 Kings 8:65
Temple inauguration feast on the 7th day.
temple dedicated to God on the 7th day of the 7th month, after 7 years, and what does God do?
And I will dwell among the Israelites, and I will not forsake my people Israel.”
1 Kings 6:13
As the glory of the Lord entered the temple by the gate facing east, the Spirit lifted me up and brought me into the inner court; and behold, the glory of the Lord filled the temple. While the man was standing beside me, I heard one speaking to me out of the temple, and he said to me, “Son of man, this is the place of my throne and the place of the soles of my feet, where I will dwell in the midst of the people of Israel forever. And the house of Israel shall no more defile my holy name, neither they, nor their kings, by their whoring and by the dead bodies of their kings at their high places,
Ezekiel 43:4-7 ESV
And God of course dwells in the temple where God rests and rules.
Until I find a place for the Lord, A dwelling place for the Mighty One of Jacob.” Let’s go into His dwelling place; Let’s worship at His footstool. Arise, Lord, to Your resting place, You and the ark of Your strength. ¶For the Lord has chosen Zion; He has desired it as His dwelling place. “This is My resting place forever; Here I will dwell [sit enthroned NIV], for I have desired it.
Psalms 132:5, 7-8, 13-14
Genesis is not about the age of the earth or earth sciences. It's about a 7-day temple inauguration where on the 7th day, God takes up the throne to rule. It doesn't have anything to do with science.