What is も purpose here?

Question

I'm not certain what purpose も is serving here. I've seen its usage as "also," etc. but I am not certain if it is being used in the same manner here or being used with a different meaning.

「きょうはやめだ。明日からもハードだろうしな。帰って寝る」
夜中の二時を過ぎたころ、彼は道子に宣言した。あくびをかみ殺して、狭苦しい運転席で伸びをする.
「そうか」
道子も特に反対はしなかった.もともと口数が多い娘ではなかったが、二四時を回ったころから極端に無口になっている。

Which according to another source should roughly translate as

「Let’s stop here for today. Tomorrow’s probably gonna be a pain. I just wanna go home and sleep for once.」
It was already past two in the morning. He said as such to Michiko. Holding back a yawn, he stretched out from the all-too-cramped driver’s seat.
"Is that so?"
Michiko remained indifferent. She had not been an especially talkative girl, but a full day of making the rounds had left her deathly silent.

Answer 1

This も means "also". The word indicates similarity.

In this sentence,

道子も特に反対はしなかった.

も fits appropriately because the thought of Michiko is similar to that of the guy. In other words, Michiko basically agreed with the guy that they go home now.

In the quoted text,

「そうか」

means an acknowldgement of what the other person said, like 'O.K.', 'alright', etc.

道子も特に反対はしなかった.

means that Michiko did not particularly voice her disagreement.

I think も can be used even when two things are not exactly and literally the same but only similar in a broad sense. For example, I can think of the following description

AとBは週末の旅行について話していたが、話に区切りがついた。 Aは、机に向かって日本語の勉強を始めた。 Bも、数学の問題にもどった。

which means

A and B were talking about their trip planned on that weekend, and they came to a conclusion. A started studying Japanese language on his desk. B also got back to his mathematics problem.

Here A and B are now doing different things, but there is similarity that they started to do their own things.