Cognitive neurologists (and psychologists) have empirically determined that typical humans can work with up to seven ideas or processes at one time. This appears to be a natural limitation of our short-term memory mechanics.
It is important to consider this when preparing demos – any demo that asks the audience to track more than seven ideas at once is (generally speaking) doomed to fail. Or, at least, it should be expected that the audience will lose track of any material that goes beyond the seven ideas limit.
In addition, bear in mind that your audience may not grant access to all seven “registers” – after all, there are other things going on in their day that they are most likely tracking as well. With this in mind, it (once again!) suggests that one should organize demos to be presented in consumable components that can be presented and easily assimilated with the remaining registers that are available.
An illustrative exercise is to contemplate you own workday – right now. How many ideas are you juggling or working on concurrently? Write them down. Now, how many “registers” are left for new information coming from someone else’s demo?