Testing one prototype or idea teaches you stuff only about that particular idea, service or product. But when you present several very different approaches to the same idea, service or product you learn way more.

There are a few reasons that make this work:

It makes people see there could be more options

When people are confronted to several things, it's clearer to them that there could be even more options out there. So they tend to not only share feedback on what you show but also on what you didn't show but that they imagine would be useful.

It forces you to open your world of possibilities

When you need to create several prototypes for testing, you suddenly realize that something that always felt as the logical right way to do something can in fact be done in many different ways, and some of these might be cheaper, faster, more meaningful, more impactful.

It forces comparison

Suddenly people who test your prototype, idea, service or product get more critical as there the comparison is more easy, And through the comparison, they often end up offering you an idea of a remix, mashup or birchermuesli of ideas and elements that come from several prototypes that they would put together to create their dream solution, service or product.

But what if I don't have time to create multiple prototypes?

First, if you don't have time, maybe it's a sign that you spend too much time on your prototypes and that you could make them simpler, faster.

But if you really think that you are on a time crunch, then you could compare your prototype with existing products, services and ideas.