Just anecdotally from browsing the Early-Retirement.org forum (note, E.R. in this case skews toward 55+ y.o. and not 35- y.o.), it seems like in the real world, folks get to 60/40 and their magic retirement number and stay around that exposure. You don't hear much about retirees using target date funds on that board.
The rub, for me, is that retiring at, say 40, gives you a really long retirement to have to fund so you are exposed to SOR risk longer (i.e. until being eligible for Social Security and Medicare). The more bonds you have, the more you are guaranteeing you will have less overall growth in your portfolio. So, on one hand, you want to have your most conservative portfolio at retirement to minimize SOR risk blowing up your all stock nest egg within the first 20 years of a 50 year retirement, but on the other hand, you know bonds have a lower expected total return and, since you have a long retirement to fund, inflation could make your real returns on bonds almost zero or even negative...
I agree with the paper you cite and the folks at ER.org, get to your number with something around a 50/50 portfolio, run it through cFIREsim and voila, depending on success rate you are comfortable with, you're FI. Don't need to get more aggressive with age, unless you really want to go for broke on a big estate (meh) and don't need to get more conservative with age, 50/50 and annual rebalance is a happy medium between low volatility and necessary growth exposure...