Could it be that the company wants its pilots try and smuggle as much as they can past the 10,000ft speed limit point until they think they can't get away with it anymore (i.e FL080) and they go for speedbrakes/level off to slow it down to a more reasonable speed?
Just an idea. I don't know how stringent the ATC are in enforcing that 250/10,000ft rule? Do you always notice when someone is "speeding"?