Could have?

Hi dear teachers. I have several questions about "could have"- I don't know if I understand them correctly.

I have some examples.

1. “If we need men so badly, why did you send away your savages?” A certain testiness crept into Cersei’s voice. “It was the best use I could have made of them,” he told her truthfully. “They’re fierce warriors, but not soldiers. In formal battle, discipline is more important than courage. They’ve already done us more good in the kingswood than they would ever have done us on the city walls.”

2. There were no more than fifty men at the trestle tables, most of them his. Winterfell’s Great Hall could have seated ten times the number.

3. Her hair could have used a wash and she had a faded pink scar on her pretty neck, but he liked the smell of her, salt and sweat and woman.

4. “No.” Pycelle struggled feebly. Shagga growled and grabbed his head. The clansman’s hand was so big he could have crushed the maester’s skull like an eggshell had he squeezed.

5. By the third day, Arya could have asked the questions herself.

As far as I know, "could have pp" has two meanings

(1) used to express counterfactual situations: you were capable of doing something in the past but you chose not to do it.

(2) used to speculate what happened in the past

So I think sentence 4 falls into category (1) and sentence 2, 5 fall into category (2).

But I am less sure about the rest sentences. They seem to fit into another category (they were capable of doing something in the past but we don't know if they did it)

Please let me know if I understand correctly.

Thank you.