Soba (buckwheat) cooks fast—4 to 5 minutes. Rinse it with cold water after. It removes the slime and firms up the texture.
Udon is a lazy noodle. Thick, chewy, it needs 10–12 minutes. But test it: It should be bouncy, not mushy. Think of it as a noodle that fights back a little when you bite it.
Rice noodles (for pad thai) are divas too. Soak them in hot tap water for 15–20 minutes. Then drain. They finish cooking in the pan. Boiling them is a crime. You’ll get paste.