For more established corporations that's usually the case, yes. As I alluded to in other comments, most companies in the US do not put 28 in writing currently.

For more established corporations that's usually the case, yes. As I alluded to in other comments, most companies in the US do not put 28 in writing currently. A subset of the "unlimited"/"flexible"/"open" PTO companies will allow you to take 28 days. Such companies do exist, I have worked at a couple already and know people working at others enjoying the same benefit. However, off the top of my head, Mailgun offers ~28 days PTO in writing. Wikimedia foundation has "flexible" vacation and 19 paid holidays.