Bought a $600 laser level for a 40x60 shop slab and it paid for itself in one pour
Everyone told me a laser is a waste for flatwork and a string line plus a couple of sasquatch levels is all you need. I fought it for years until a 40x60 shop slab in Nampa last spring had a screed run 3/8 inch off at the far corner because my string sagged in the afternoon heat. Dropped $600 on a rotary laser with a receiver, set it up once, and finished that pour with zero edge chipping and the flatness numbers came back clean. I have used it on every pour since, but I still keep a string line in the truck for tight spots. What are you all using to hold grade when the wind picks up and your string starts acting up?
That's why the old timers ran a line on both sides and checked mid span, saw a guy on a job in Boise do it that way for years. Past 15 mph the string is useless anyway, so I just move the laser and reset the receiver on a stick.