This is a 10-part ecourse that goes over the subject of live demostrations. Live demos provide a great way to interact with and educate potential customers. However, can you go overboard? As long as you are reasonable, you really can't go wrong with how many live demos you have. In other words, you should have live demos as often as possible.
However, if you struggle to get an audience and most of your presentations run without anyone watching, then it might be a better idea to pull back. Live demos should be focused around your audience and if no one is showing up, you need to look into creating a better marketing strategy. On the other hand, if you don't struggle with getting viewers, then this is another indication to keep having the live demos.