It's become a luxury to ask this question now with the pacified early warring, which used to answer the question for you as you knew you'd need several archers super early. For me, no, I rarely build any early, because you can either farm barbs for the first 30, or if you actually need them there and then, well that's exactly when I wouldn't have time to build the barracks/armoury anyway. Heroic epic regularly tempts me to get barracks up if I'm going tall, but I generally regard it as I luxury I can't afford as there are always more important things to build, especially if I'm doing so poorly that I have few enough cities to realistically consider this. Later on, sure, if there is nothing better to be building, or if you go Brandenburg (again, the 3 promos off the bat are tempting for GWBs, but it's not that far to go if you don't, and I usually want to focus on something else better), but I rarely spend more than a couple of turns on them. In conclusion, the best help for an army is a strong economy and productive cities, not explicit military bonuses.