I rowed in college, we experimented with different riggings (including arrangement 'a' from the article) and found that, indeed, bucket-rigging and others seemed to yield good times. There were other variables though, strength of the current, wind, how intense our hangovers were... so it's hard to attribute it to just the different arrangements. I will say that sitting in an arrangement where the guy in front/behind has his oar on the same side as you leaves very little room for error. If you don't get that oar up and out at the finish you'll hit oars and crab for sure.
The start and finish of the race are located at fixed points. If you're racing on tidal rivers near the coast, where most of our regattas were, the current varies widely throughout the day. Say it's a 5k head-race starting upstream and coming down towards the sea. At high and low tide you're essentially racing with no (or very little) current - much like a lake. When the tide is coming in, you'd be racing against it and a 5k race can take 20 or more minutes. If you're lucky and your race heat starts when the tide is going out, that same race will take 15 or less minutes.
