同じ一日 - Is this a common phrase?

Question

I saw 同じ一日 from an example sentence: 今日はいつもと同じ一日だった。

Is this phrase commonly used? Is it similar to 今日も一日?

Answer 1

This 同じ is a 形容動詞 (called na-adjective in English) that modifies 一日 (a day). I wouldn't call 同じ一日 a set phrase like 今日も一日. It is just a noun phrase composed of an adjective and a noun. 同じ, when used before a noun that it modifies, often occurs without な.

For example, 彼と同じ学校だ means "the same school as the one he attends"

今日はいつもと同じ一日だった。

Just means

Today was just another day, same as usual.