That's correct, but still not a full picture. Most wonders, you'll already have a +100% multiplier (Pyramids with stone, for example). In that case, Industrious bumps you to +150% production, which is only a 25% bump.
(Here's how to do the math. For Pyramids with stone, each hammer you work is 2 hammers put into the mids. For mids with Ind and stone, each hammer you work is 2.5 into the mids. The extra 0.5 is 25% of 2).
Got more multipliers, like Forge and Organized Religion? Ind's bonus becomes less meaningful.
I find that Ind is useful for 2 situations:
- Early game wonders where you have the resource. Here, everyone probably has the tech, so it really is a race to produce the building, and a 25% bump helps you do that. (If you don't have the resource, you'll probably still lose though).
- Later wonders where you DON'T have the resource. Later wonders, you'll usually only go for if you get the tech first, so it's not really a production race. That means you can go for wonders without having the resource, but it's painfully slow. Ind makes it less painful.
Later wonders where you have the resource? 20-25% production bump is nice, but nothing to get excited about.
Those two reasons, and for failgold. Getting an extra .5 wealth per hammer "free" is nothing to complain about no matter what point in the game you're at.