&gt;TIL that other people problem solve by talking in their heads!? 

How do you take quick notes without a writing it down?  
If someone gives me their phone number I just repeat it in my head a few times and I will remember it. That would count as an inner monologue.

&gt;Ok, so since I'm apparently weird, I just visualize everything 

It's not weird at all. We all do this as well, if possible.

Visual problem-solving works wonders for puzzles, games, driving, painting and other visual stuff.  
But numbers and language don't have any visual representation.   


If I'm gonna make a phone call to my boss. I usually think about what I'm gonna say before in my head. To know the possible ways to steer the conversation based on his replies. If you are not making this inner dialogue. How do you plan ahead this?