180 to 6NM shouldn't be an issue (not in any commercial jet I've flown). If the aircraft is not doing what you want it to do, create drag (higher flaps or gear down). Shouldn't be an issue, especially at higher landing weights.
The tricky part might be 160 to 4NM (with very light weights which require a large speed reduction to final speed). But normally you can solve this with the same solution: continue to configure but maintain the higher speed. The already present drag will instantly reduce the speed of the aircraft from 4NM.