Three curls / four curls is actually a good playcall on first down because it gets you ahead of the chains and sets up short 2nd downs. It's also an extremely effective playcall on, say, 1st and 20 after a penalty, because it pretty much guarantees you get roughly half your penalty yardage back and can salvage the drive. McCarthy did that a TON in the Rodgers era.
It's a bad playcall on third down because other teams know it's coming and they will guard the sticks like a hawk, so the windows are very tight to throw if they are there at all.