Why is screenprinting so hard? It isn't hard in the sense that it is a difficult medium to learn. Screenprinting can be physically demanding once you learn the basics:
1. Always have half a cup of black acrylic paint and an equal half measure of acrylic printing medium.
2. Stir with a spoon until it has a nice runny texture.
3. Now you are ready to print onto your watercolour paper, make sure the follow-through with the squeegee begins at the shoulders, not your wrists or hands.
So, back to the question: why is screenprinting so hard? I refer to stamina. I think that if you print seventy-five pictures, that's a test of your stamina. At that stage, you should perhaps take a break and return to the job in hand.
Or maybe I have little stamina? Now we'll never know....