Or is it still a case of waiting for some hormone or other to kick in? DS1 (4.5yo) is absolutely fine going to the toilet during the day, but still wets heavily at night. He always has a big wee before bedtime and doesn't drink especially much between coming home from school and going to bed (250mL of water or milk at the very most, if that). I can count on the fingers of one hand the times he's been dry at night and they've never happened on consecutive nights.
DS2 is 2.3yo and nowhere near ready for potty training. I'm sodding fed up of effectively having two in nappies. 