Drain nodes one-by-one

Dedicated issue for the comment I left on #6267

> A second possible improvement that this issue highlights is that for draining nodes in general it would likely be optimal to do them one-by-one (even when draining them all at once).

Draining nodes is usually done so that you can remove those nodes afterwards, often for cost saving purposes. By draining nodes one-by-one, it's possible to remove the first of the nodes before all of the others are drained. In time critical scenarios this can help quite a bit.