I talk a lot. Sometimes it's quite spontaneous stuff. Occasionally I end up saying the wrong thing, but usually it's OK.
HOWEVER
If I am in a situation that requires a carefully framed response, the old processing delay thing kicks in. I can't respond appropriately, verbally, in real time. I need to think it through.
I can write it down, or I can come back a few minutes later and reply verbally. Either works in the right scenario.