Since I rarely build catapults or trebuchets unless my unit 'edge' is lacking, for instance against a strong civ with Great Wall, I tend to build Barracks before I spam 5 or 6 cannons, around about the time I'm going for my 4th, 5th or 6th capital. At this time, production is usually good enough that they take a maximum of 2 turns to build, plus another 3 for an armory.
That way, the newly-built cannons get Accuracy/Barrage 1 and Volley 1. I position them on the 2nd ring between the meat-shields and the Gatlings with Range, and very few capitals can withstand more than a few rounds of that.
Not giving them volley only seems worth it if you've not done much warring prior to Chemistry. To my mind, spamming catapults/trebuchets seems like a poor use of hammers since with Honor, my Gatlings/XBs/CBs will do whatever I need anyway.
In my latest game, the ICL game with Poland, my starting 5 archers all survived to Chemistry with every possible promotion, to be turned into UberGatlings.
[EDIT: Also, they are a no-brainer if you choose the happiness tenet in Autocracy. 10 turns and each city can have +3 happiness if you build barracks, armory and military academy with decent hammers. If you take lots of cities late game and annex them, you can pump out the war buildings before you choose Wealth or spam meat shields]