A twenty-minute event conversation can be enough in some cases, but the better question is whether the consultant has enough information to feel comfortable endorsing you.

A referral is not just a networking reward. The person is attaching their name to your application, so a good conversation matters more than the event setting itself.

If the discussion was substantive and they encouraged you to stay in touch, a brief follow-up can be reasonable. If it was mostly introductions, asking for another short conversation first is safer.

Use the relationship you actually have. Do not force an extra coffee chat as a ritual, but do not ask for an endorsement the person has no basis to make. A concise, evidence-based explanation will usually sound stronger than a long defensive one. For more detail, see the consulting networking guide.

Twenty minutes can be enough if the conversation was actually substantive.