Personally, I think it's okay to interrupt all depending on the situation and the person you're interrupting. If you do it politely and you know the person won't get super upset then I think it'd be okay, especially if you don't do it often.

There are also levels of interrupting someone, sometimes we completely cut them off and go straight into what we want to say, and other times we can just say "I disagree but continue" or "that's factually incorrect" and then let them continue. Sometimes people will wrap up what they were saying and then ask why you disagree or wait to hear what you have to say. Interrupting is actually fascinating because it can either go very well and both people kind of read each other's voices, words, and body language and respect the other person's choice/need to interrupt and other times it can go horribly wrong lol.

I think, in general though, interrupting isn't the best to do often and best not done aggressively. Try to let the person finish as often as possible, and if it's hard to hold onto your thoughts, jot them down so you don't forget them, there's nothing wrong with having to make notes if you're having a serious conversation. If the person is aware you're doing your best to make sure you have the best level of communication possible they shouldn't mind the note taking.