Always seems hit or miss for me. Often one checks a load and it seems a bit too damp still, so reset the timer for another ten or so minutes (before cool down on the "Normal" cycle) but usually when one checks again (after hearing the click that indicates the heating is being shut off for the cool down phase), laundry is usually hot/bone dry.
Have always wondered if the heating power could be increased by swapping out a higher voltage element. IIRC vintage full sized Frigidare dryers that could run on 120v went up to around 1800 watts. Now that would be something.