If you go back 20 years or so to the days when the "Flight" directories were fairly serious works of reference, you'll find exactly what you describe. The mass flow rates at maximum sea level thrust range from about 100 kgs per second for the Spey up to 744 kgs/second for the JT9D-7Q. But in the cruise the -7Q, which generates 53,000 lbs on take-off, drops to 8,500 lbs of thrust, and the mass flow rate drops to 285 kgs/sec - very much in line with the calculation by Genghis.
[Is there still a market for a magazine today like "The Aeroplane" was 40 years ago? A subject for another thread on another day, or maybe no thread at all, but the volume and weight of really serious data and analysis carried week after week was formidable. I bought a dozen copies from the mid fifties a few weeks ago - the adverts were more informative of aviation principles than a year's copies of "Flight" (area rule, semi-active radar homing and the principle of the free turboshaft all being explained in the ads of one issue alone)].