This is actually such an interesting topic - 明白了吗?/ 明白了 is something I heard ALL THE TIME in Chinese classes in the mainland, but it’s something I barely ever hear in Taipei. Instead, I’m usually hit with a ‘懂吗?’ or if I explain something to someone, they’ll often reply with a 了解
There’s also a contextual difference between 了解 and 理解, but I can’t remember what it is does anyone know?
Good to know 理解 can be used for more emotional topics or to sympathize with someone, that could definitely come in handy. Also love the quiz at the end of the video