It takes a lot more information than that to know how productive a manufacturing line is. How many shifts per day do they have? What's their preventative main

It takes a lot more information than that to know how productive a manufacturing line is. How many shifts per day do they have? What's their preventative maintenance schedule like? Are they doing any retooling? Any line that's not running nearly 24/7 is underutilized, but retooling can trade some downtime now for a permanent increase in output. If a manufacturing line goes from three shifts a day to two, that's a significantly larger decrease than taking a few days off per month. Assuming that they're only ruining a single shift, and that the downtime is because they're outpacing demand, this does give us some information about what their utilization is, but even that doesn't tell us how well a product is doing. Keeping inventories low can decrease some costs and is especially incentivized by some tax regulations, but it requires fast increases in production, which is easiest done by building out more manufacturing capability than is expected. tl;dr: If you want to know how well a product is doing, look at the sales figures. If you want to read into the strategies the manufacturer is making, scrutinize the assembly line.