So when you hear an American crew using this style on the radio, they are not being sloppy but actually doing what they have been taught.
True... we're sloppy in other ways!
Altitudes are generally given as: "Two-thousand five-hundred feet" or "Flight Level two-five-zero".
Headings are always "Turn left to three-six-zero"
Squawks can be given as "Squawk twelve-hundred" or "Squawk VFR", but IFR squawks are given as individual digits.
Callsigns are contracted numbers... depending upon the radio strength, they may be given as single digits for clarity until there's a positive ID. Sometimes an aircraft will roger as "Cactus 49", but only after established with the controller.