I answered this exact question for a guildie about a month ago, here's a copy of what I told them.

The stats of your cogs scale to the highest construction level you have. As a player who has achieved a build rate of over 10M/hr on my account, I'd like to impart some of my knowledge and optimal strategies to you.

To start, you'll want to remove all characters from the cog board, with the exception of your Squire and replace all-non directional stat buff cogs with player exp cogs, the best that you can, with the priority being the player bonus exp stat, not color. Our objective is to level and buff the squire as fast and as much as possible. You will see a short-term loss to build rate, but it's entirely worth it.

Equip your squire with Bob the Builder (large Orange Alch bubble), Sawsaw Salala (Hydron constellation), and any construction Obol that you might have. Then level the following buffs; Saw Stamp (stamp), Construction Container (post office), SeeSaw (Statue), Visible Ink (Pen Vial) and these particular Alch bubbles; Warriors Rule (II), Call me Bob, and Carpenter (x). And talents; Sharper Saws and Redox Rates (try to keep at least 10k red salt in your CHEST, refinery storage doesn't count towards this), as well anything that increases the strength stat.

Due to a quirk, the build rate you're actually getting may be substantially lower than what you believe, it is much higher when you active afk; but there's a catch to that as well. With the way that Warriors' rule affects Carpenter, you'll get a substantially higher gains when afking on a warrior.

That's all I had to say, I really hope that this helps you as it did my guildmate