I’d never claim that the plank is a "bad" core exercise. It’s great for working the deep stabilizing muscles in your core as well as your abs and lower back, and it’s an approachable move that most people can do in their workouts.
It’s also very boring, in my opinion. While isometric exercises like the plank, where you hold a position to challenge your muscles, are effective, doing your best to stay still for long periods is not my idea of fun, and I much prefer workouts made up of dynamic core exercises.
