Front to back isn't a bad idea; I haven't seen that one before, but I haven't flown Delta in a while. I prefer sitting in the back, and it would really suit me to keep out of the plane as long as possible, so this would be great.
I had heard that window seats, then middle, then aisle was really fastest, but I've never been on a flight where they did that. They'd have to figure in people flying together.
Airlines have made so many exceptions for boarding order, mostly unnecessary or profit-driven. Mobility impaired, people with small children--sure. But then there's first class, premier seating, whatever loyalty tier, etc, etc. Last time I flew United, they had six different lanes, only partly based on where in the plane your seat is.
Don't get me started on how the pay for flight attendants starts only after the plane door closes. Explains the constant nagging for people to put their belongings away and get in their assigned seat. Most people are motivated to get in their seat, and putting things away takes as long as it takes. The nagging is just unpleasant and mostly unnecessary.