There are clear arguments for and against taking questions at the end of a presentation as opposed to taking them throughout, and different approaches are suitable in different settings.
The benefit of taking questions throughout a presentation is that it allows you to immediately address issues that are relevant to your audience. If you are in an intimate business meeting or an interactive training environment, this can be a great way to encourage engagement and to ensure that you are covering the topics your audience is interested in. Taking questions throughout feels more informal, and the relaxed atmosphere can help presenter and audience better relate to each other.
The problem with allowing the audience to ask questions throughout is that you hand over control. Allowing the audience to interrupt you with questions means that you risk running out of time and not getting the chance to deliver all of your key messages.
The argument for taking questions at the end therefore is that it keeps you in complete control of structure, content and timing, enabling you to ensure that you get your key messages across in the allotted time. This approach is far more practical for a formal or keynote presentation. Allow time for questions at the end, and you can have more of a conversation with your audience once you’ve got your point across. If you then find that your audience members have further questions they would like more detail on, you can always follow up at a later date. This can be particularly useful in a sales setting as it encourages contact beyond the presentation.
So, as always, the answer is: it depends. In most cases, and in formal settings, we would suggest leaving questions until the end. But in training sessions, or if you’re in a less formal meeting with fewer audience members, taking questions throughout can improve audience engagement.