The person who says “I’m not sure, let me check” is more trustworthy than the one who always has an answer.

Somebody who always has an answer is either extraordinarily well informed or not distinguishing between knowing and guessing, and from outside those two look identical. A willingness to stop and check is a signal about method, which is the only thing you can really judge from where you stand. Over time the person who checks is right more often, and you learn which of their statements you can lean on.

Use that sentence yourself this week instead of filling a gap with something plausible. Then go and check, and come back with the answer.