It's about the angle your left wrist makes to hit that top row. If you only extend your fingers linearly, keeping a staggered keyboard aligned with a "neutral"

It's about the angle your left wrist makes to hit that top row. If you only extend your fingers linearly, keeping a staggered keyboard aligned with a "neutral" left wrist means basically a 90° angle. Anything less and you're twisting your wrist horizontally. For me that's the most painful, and anecdotally I hear twisting your wrists is a notorious contributor to injury. But, as always, do your own randomized controlled trial if you want to be sure :)