Hello Scopov, no problem, I'd much rather you ask for clarification than walk away from the lesson confused.

I totally get where you're coming from. Having done some studies of human skulls, I'd agree that the eye sockets are fairly rectangular (for humans, at least, I can't speak for all the variety of animal skulls). Keep in mind that the construction methods we teach at Drawabox aren't necessarily anatomically correct, but are tools to help students develop their spatial reasoning skills.

The pentagonal eye sockets used in the informal head demo method aren't perhaps going to be something directly observed, but that pentagonal shape is really useful for wedging the base of the muzzle and forehead plane against. This is considerably more awkward with rectangular eye sockets as shown here. This is all part of the exercise Uncomfortable wants students to go through when constructing heads- transforming the round cranial ball into a series of planes. I hope that shows why the pentagonal shape is helpful, even though it may not be anatomically accurate.

As for your other question. I don't know if your attempts at redoing your constructions were objectively worse, but I can tell you from my own experiences that I often find redrawing the same reference frustrating as I feel like I should be able to learn from the first attempt and do better, which doesn't always happen. So I would say that your experiences are normal, though I'd encourage you to ask about it over on Discord to hear a wider variety of other students' experiences, and open up a discussion on why people think it happens.