FMS usage and application for ATC purposes
When a clearance to climb to and maintain FL 220 is received, the FL (220 in this case) is set into the Mode Control Panel (MCP - Boeing phraseology). The altitude button, also located on the MCP is then pushed. If in VNAV, the aircraft will climb more slowly and on profile up to FL 220. More often than not, FL 220 will be set into the MCP and then Flight Level Change (FLCH) will be selected. Boeing programs FLCH, so that the aircraft will attempt to reach the new altitude within two minutes (if possible, which on longer climbs is obviously not). By depressing the Altitude button on the MCP, the revised altitude is automatically introduced into the FMS, requiring less "heads down" time in theory. I never heard of this practice of placing a higher altitude in order to facilitate a faster rate of climb. I've personally never witnessed anybody execute a change in altitude in this manner. I hope that helps.