If the goal is to collect precise data and use it after the experiment to draw conclusions, update a model, etc. then sure.

If the goal is to demonstrate to observers how the neutron output (reaction rate) increases as the reflectors are moved closer together over the source, then that isn't really necessary.

This seems more like an incredibly dangerous version of a demonstration you might see at an interactive science museum or a classroom. You don't need precise measurements to demonstrate the relationship between two phenomenon.