On the other hand, since you don’t know future requirements, it’s easier to refactor/abstract unabstracted code than to refactor/reabstract already-/wrongly-abs

On the other hand, since you don’t know future requirements, it’s easier to refactor/abstract unabstracted code than to refactor/reabstract already-/wrongly-abstracted code. Function extraction adds indirection that doesn’t necessarily pay its own rent. It’s not free.