Before my recent layoff, I worked in a textile mill. The only time my toolbox was unlocked was when I was getting something out of it.
I know the title is about work, but, I lock my boxes at home.
My reasoning--- If theives were to break in they would have to try to take big, heavy, awkward to carry boxes.
Instead of just opening the drawers, grabbing chrome stuff, and running away.

I know the title is about work, but, I lock my boxes at home.
My reasoning--- If theives were to break in they would have to try to take big, heavy, awkward to carry boxes.
Instead of just opening the drawers, grabbing chrome stuff, and running away.
Yep, and mine was kept inside a locked cage area, but people still came and helped themselves so I started locking it anytime I wasn't actively using it. At first it was a PITA, but after a while I got used to it.
I wound up making a hand tool box for the management for when I wasn't there (company paid for it and the tools in it) with screwdrivers, allen keys, wrenches and such in it. Most of those tools were lost or grew legs within just a few months.
My boxes at home are unlocked, but I'm rethinking that - it's not that we have a theft problem in the 'hood, but I'm just more security conscious these days.