One thing I've noticed that can improve prep times is taking a basic knife skills class. You'll notice grandmothers who have been cooking for decades are often pretty clunky with a knife. There are still some things that you have limited control over that will slow you down: counter space, kitchen layout, sink size, or what bowls and pots you have.
Years ago I feel like they had more leftovers. Usually, it was the side dish where they gave you a whole head of cabbage instead of half to prep. It was usually mentioned in the recipe. I had been meaning to look back to see if they amended the recipes when they repeated them removing the leftovers--but I haven't used Blue Apron in probably a year now.
I'm glad you learned that roasting vegetables are dead simple and delicious. I feel like growing up with canned and boiled vegetables this was somehow a well kept secret until recently. But there are other meal-kits out there that vary widely on complexity and prep time.