I found that putting thoughts into words was a skill that became much easier with practice. And then I realised that it forced me to structure my hunches, which would knock some of them out on the spot.

What I did at first was as you describe - chasing down lines of thought quickly, then saying what I thought the answer was. Then I learned to vocalise it through practice. And if I need a moment to think, I can just say "gimme a sec to think" or "can I take a break?" and that's all it takes.