How much should I oversample/undersample?

Instead, you should ask what objectives and constraints you are optimizing for

If you've ever had a class imbalance (1:50 or similar) and asked:

"How much should I oversample? 2x, 4x, more?!, Or should I undersample 60%?"

It's the wrong starting point because sampling is a tool, not the goal.

Instead, it's helpful to start by aligning the objective within the constraints you are working with. Think of things like business costs, eval…