I’ll set the timer for 2-8 minutes, and I’ll only use high flow acrylic ink in carbon black and a no. 4 round brush.
It’s a really fun exercise to do, allowing yourself one medium & a time limit to make something. I do this quite often, to be comfortable under pressure, to go after that effortless translation of whatever I’m drawing. I also don’t have time to fix mistakes, and so I embrace them!