For low alt cruise, you normally climb at an IAS that roughly equates to your intended cruise speed.
Climb and cruise at 300 IAS
There is an old saying: climb fast, cruise slow. (But not that slow!)
Yup.
In addition, the same is true for large widebody aircraft, flying longer sectors (at higher levels) at a very light weight...ferry, for example.
Instead of climbing normally (250/340/M.835) as you might at heavy weights, a slower climb speed (250/285/M.80) would be desired, and combined with a slower cruise speed (M.81) would demonstrate significant fuel savings.
Fuel...waste not, want not.