In a more complex example where you actually take a variable, do some operations to it, then reassign it, Pluto.jl encourages you to separate that into multiple cells. The reason is each cell marks a distinct node in the dependency graph. If you prefer to use cells, then the notebook can be smarter about what lines actually need to get re-run and what don't.

A downside to using multiple cells is vertical spacing/visual noise. This is something that the package authors are currently thinking about addressing.