Especially if dancing
I learned this one the hard way on Tuesday. I was away at Resistanz over the weekend, and then on Tuesday I was out all day being an extra in a film called Of The Shadows, during which I was in a ballroom scene.
My liners needed to go through the wash and I didn't have time to get them dry before going out to be filmed, so I just whacked on my corset with nothing on underneath it, then on top I had a bustle gown, and they can get quite heavy at times, so the gown put a lot of pressure on the corset, and then we had to dance for around ten hours, all the time the dress putting pressure on my corset laces.
When I got home and de-corseted I discovered that I had managed to blister my back and now I can't lace up again until it heals.