Most of us practice some form of instruction in daily life. For the teachers, instruction comprises the bulk of work. For the rest of us, instructing people is common and it is necessary to co-ordinate actions between working parties.
Coming from the viewpoint of an instructor, we expect our instructions to be heard diligently and to be delivered effectively. I don’t know about you, but I think most of us dislike being questioned during or after the period of instruction. I guess it feels like the person questioning you is disrespecting you. Though this may seem true on the surface, I've come to realize something quite to the contrary. Sometimes being questioned is a good thing.
When we listen to someone's instructions, we construct a general idea of what the person is saying. Even if the person gives us elaborate instructions, our minds can only catch hold of that much information at once and thus, we only form a general idea of what is being said. So for example if a person is telling us how he wants some excel sheet done, we will get the general idea of it but we'll tend to miss out on the minor details like maybe how big he wants certain columns or what information he needs the most from the file. These details, though minor, actually matter the most.
And this is where inquiry comes into play. Inquiry bridges the gaps within the general idea conceived from instruction. It helps make the instruction given that much more complete. For the person mentioned above, only when we ask about the minor details of the sheet will we be able to fully understand what he wants.
With this in mind, I would actually be quite worried if the people I'm instructing have nothing to say at the end!