Increasing the number of vehicles in the fleet lets one consider alternative transfers, like the bi-elliptic one mentioned in the article.
...though it might make matters a bit difficult that expected durations vary between 300-ish days and 4 years when I run the numbers in NASA's Trajectory Browser: https://trajbrowser.arc.nasa.gov/
Also, Earth Mars transfers get dramatically more expensive outside of specific timing and of course actually sending multiple packages gets ruinously expensive. https://en.m.wikipedia.org/wiki/Hohmann_transfer_orbit