Given scene/plot descriptions from movies or TV shows, and given a specific question about the scene, summarize the question into a title

Why did they have to choose a different person each time they went one level deeper in Inception? Couldn't they have kept going into Yusuf's dream all the way down?
Was it impossible to go into same person's dream each level down, or did it serve a purpose?

I haven't finished Z for Zachariah yet, but is there radiation in the water and an intense scrubbing will protect you from it? Why does Margot Robbie wash Chiwetel Ejiofor in Z for Zachariah?
Why does Margot Robbie wash Chiwetel Ejiofor in Z for Zachariah?

In the iconic Battle of Stirling Bridge scene in the film Braveheart, English heavy cavalry knights charge with a lance in their right hand and a shield in their left hand. I recently watch this battle scene again and noticed one particular thing: English knights should have carried close quarter melee weapons. I understand for heavy cavalry, they are supposed to charge towards their enemy over and over again on their horses, but should they not consider taking a melee weapon with them, for example, a mace, a sword or a dagger so that they can defend themselves when they become dismounted. I think it is a detail Mel Gibson overlooked when making this movie.
Are the cavalry knights missing close melee weapons in Braveheart?