Based on a boeing recommendation we changed our speed policy below FL100 to max 300kts and max 250 below 5000', originally for a mix of 737 classics and NGs, nowadays NG only. Company policy is 250 below 10, the limit up to 300 may only be used on request by ATC. And i guess everyone has a schedule to keep, its just a question of how it is planned and that is more of a management decision (net management) than a pilot decision. If net management plans block and turn around times that are impossible to keep they will have a problem with airport slots sooner rather than later.