Short Sleeved Lab Coats

Surely the point is when preparing chemicals it acts as a few seconds of safety - enough time to rip off the lab coat before that conc acid gets on your skin. I roll them up when they are in the way, and I don't wear them unless in lessons or dealing with hazardous chemicals. (Yes, I get splashes sometimes to my t-shirts have more holes and bleached patches than is normal, but they are cheap and expendable).
Having said that, this is a chemistry issue not a physics one and not so much a biology one.
I use an apron for most things (better pockets and cooler - our building is over-warm), but lab coat for tasks that require it. This includes biology, at least for the microbiology activities.