This is exactly what most of the big firms do, they know they'll get snagged on a certain amount of the work but it still pays.
Course it does, I did my time On sites for 4/5 years day in, day out driving 60 Miles to hull and back, 40 miles to Wakefield and back, Scunthorpe, Grimsby and even Exeter for £2 m2 without digs
2 of us, telling ourselves the rates would improve, they didn't, they haven't and they won't.
The only decent money we made on site was float and skim £6 m2, they saw we made £150 a day and dropped it to £5.
On site you make what they want you to make.