randomboolean No, the laptop is connected to the monitor always.(0 brightness, 0 contrast for monitor) So laptop screen stays off. Only app I use is 'Iris Mini' with brightness 75%, and Temperature 5000K. Even 0 brightness was bit too much for my eyes, so is use Iris.
One thing I forgot to mention is monitor contrast ratio can also play an important role, usual monitors are 1000:1 . Fortunately, the Lenovo one has 1500:1 contrast ratio. So we get pure blacks and whites .
(When I have to use the HP laptop screen, I keep running 'Ditherig' app with 'disable all ditherig on ) , movies and media will look bit noisy, like gradients are broken. But it helps me to reduce the strain for around 2 hour. Then a break ,Facewash, look far, back to work 2 hour again loop. Contrast 0, Brightness 64 on intel control center, here laptop fn key brightness is still zero. This gives a bit washed out look. But it's comfortable. This value is a result of my continous testing & failing. But it depend on the Laptop, my HP is Glossy screen. So it will be different for Matte screens. Tip is test different values till you feel like screen is good, I can read comfortably.And screen should look like it is part of your room , like in brightess, say similar to a open book white page in that room, Then go with the values for a day.
if you want the links, let me know.