“It costs nothing” often means no money changes hands. A request can still use an hour of preparation, interrupt an evening or leave someone responsible for the work afterwards. Those costs do not vanish because they are difficult to put on an invoice.
Name the time that is being borrowed
Imagine a voluntary committee asks a member to give a ten-minute presentation. The visible commitment is ten minutes. Finding the information, making slides, travelling and answering follow-up questions may take much longer. This is an illustrative example, but the distinction is useful in many settings.
Before calling the request small, describe the complete task. Ask which parts are essential and which could be removed. Perhaps a short written answer would meet the same need without requiring a live appearance.
Make refusal possible in practice
A formal “you can say no” may be weakened by a public request, repeated reminders or praise that implies a good colleague would always agree. Consider whether the person can decline privately and whether an alternative genuinely exists.
This does not mean every request is unfair or that all time must be priced. People often choose to give their time generously. The ethical question is whether they can understand the commitment and make that choice without having its cost minimised for them.
Try rewriting a request with three details: what outcome you need, the realistic preparation involved and when an answer is needed. Then add an alternative that you are actually prepared to use. Do not invent a fallback solely to make the wording sound considerate.
Afterwards, compare the expected time with the work the person really did. If the task expanded, acknowledge that and change the next request. Respect for time becomes visible through smaller scope, clearer expectations and a willingness to accept a refusal, rather than through repeated assurances that the favour is free.