Optimal repaint strategy

Is this an optimal repaint strategy? What happens if i have 10 of these running with different positions in diferent bits of the screen?

class LfoPositionIndicator : public Timer, public Component
    LfoPositionIndicator(DuckPumpAudioProcessor & p): processor(p)
        setInterceptsMouseClicks(false, false);

    void timerCallback() override
        x = roundToInt(float(getWidth()) * float(processor.getPhasorPosition()));

        repaint(lastX, 0, 1, getHeight());
        repaint(x, 0, 1, getHeight());
        lastX = x;

    void paint(Graphics & g) override
        g.drawVerticalLine(x, 0.0f, float(getHeight()));

What do you want to achieve with the two repaint calls? I guess it’s probably more effective to just call repaint() once.

The areas may be spaced apart if the pointer moves by more than one pixel. They usually are moving by 10 - 20 pixels.

is there a thing with how computers paint the display in horizontal scanlines, so calling g.drawVerticalLine might in fact be awful? is that something to think about for repainting?