Is an inner monologue supposed to be completely intelligible, or at the same speed as spoken conversation, or in complete sentences, or always on by default? B

Is an inner monologue supposed to be completely intelligible, or at the same speed as spoken conversation, or in complete sentences, or always on by default? Because I can, e.g. look at the painting on my wall and summon a voice and think "ok what do I think of this painting?", and then I start getting random ideas like "blue sky" and "leaf, leaf, leaf" and "that's a weird curve" and "I'm getting hungry". But it's not like a fully formatted paragraph with coherant thoughts, in fact the voices are almost always overlapping, like someone is speaking 3 or 4 things at once and I can sort of hone in on one or two of them at a time. Then when I stop thinking about it, my mind fades back into whatever it was on before, usually some music that's stuck in my head (which interestingly is always in the correct key and tempo even if it repeats the catchy bit more than it should if I'm not paying attention). The weirdest part is that when I'm actually listening to or playing music the narrative DOES actually collapse into a single spoken-conversation-speed track.