would + verb construction

would in this sense is an idiomatic way of speaking about past habits.

To talk about past habits we mostly use 2 constructs.

1- used to - with a simple past declarative clause with a to-infinitive clause as a direct object .

e.g.

He used to clean the dishes after him. Now, all he does is leave a mess behind.

A past habitual action that no longer happens.

2- would - with an infinitive verb

e.g

We would look at each other all day when we were left alone.

Again a past habitual action, but unlike used to, can still happen today.

Two big differences though, as they seem interchangeable.

the fist:

'Used to' can be used to talk about past states as well as past repeated actions and habits, but 'would' is only used to talk about past habits. 'Would' is not used to talk about past states.

The second (as with your example)

Used to doesn't work well in a negation clause whereas would does.

Would is used in these ways:

Past tense of will

My grandfather was a very fit man - every day he would go jogging. - Past habit (Used to).

He said he would do it tomorrow. - Reported speech. (Past tense of will.)

I wonder how tired those people would be" Reported speech and an indirect question. The direct question is “I wondered, ‘How tired will those people be?’.”

He wouldn't help me. - Refusal in the past.

“If I asked him, he would not help me.” (See conditional below.)

I would say that he is about 30 years old. – Softening, or expressing some uncertainty about, an opinion. (Also See hidden conditional "If I had to decide, I would say that he is about 30 years old.")

One day he would become president. - Future in the past.

Subjunctive: I wish he would stop doing that. – Pseudo-subjunctive. Regret about somebody's [current] behaviour or habits.

Third conditional

If he had heard the weather forecast, he would have started earlier. - Third conditional expressing a high probability.

Would you like to have more coffee? – (i) Polite offer (ii) Part of a hidden third conditional = If I were to ask you, would you like to have more coffee?

Would you help me with this? (i) Indirect question (ii) part of a hidden third conditional = If I were to ask you, would you help me with this? (iii) Softening a request/a polite request.

Probability or Possibility

Be careful! It would break if you dropped it. - Predicting a high probability. Well, he would say that, wouldn't he? - Commenting on the high probability (of his saying that) based upon his typical/habitual behaviour.

The past tense of the full verb “to will”

I would rather you didn't do that. Past tense of the full verb “to will” (= {(to wish or want) + rather (adverb = preferably)} = Expressing a preferential wish about an action

Compare the subjunctive use in Byron’s poem: “I would I were a careless child, Still dwelling in my Highland cave,”