They mention that boarding even rows first and then odd rows is also an improvement, but I've wondered whether 2 is actually the right periodicity. If we suppose a row consists of 6 people with roller bags, what we really want is to ensure that all 6 of these people can occupy the aisle without blocking anyone else from their row. So what if we used 10 instead of 2? I.e. first board everyone whose row number ends in 0 back to front, then everyone whose row ends in 1, then 2, and so on.

(I assume you could do even better by boarding window seats first, then middle, then aisle, but keeping rows together is much more family/group-friendly.)