As seen in this tutorial, adding a Waves modifier to a subdivided plane results in multiple concentric ripples - and that's the behavior I remember from versions of Blender prior to 2.8.
However, when using 2.8 and adding a Waves modifier to a subdivided plane, I seem to get only a single wave which deforms the plane, even when editing the Width and Narrowness etc values.
How can I recreate the earlier behavior with the current modifier? Sorry if this is a dumb question, I've been messing about with the modifier and I'm somewhat baffled.
EDIT 02: I downloaded 2.77, as this is the version Gleb was using in his tutorial (linked above) and the Waves modifier works identically to how it works in 2.8, requiring extreme values to create multiple ripples.
Default values, no changes to width or narrowness and yet there are the desired ripples…!
I think I’m going to have to chalk this one down to gremlins.