From my personal experience with sewing clothes entirely by hand, it still takes time. The time to sew it and the time to sew it right enough. Going back and forth fixing little mistakes and trying to make it fit better. I suspect that’s also true for people who sew with machines and make clothes for others.
There’s also going to be the drive to get it done efficiently so, whether by working with multiple needles on the same garment (trust me, that’s been my experience) or with machines. Some fashion companies have been trying to refine this process to meet with market and consumer demands.
But it still takes time to make clothes, whatever material you work with.