Cruising Levels:
Your filed cruise level will be used in planning sector throughputs and capacities a long time before you get airborne. Any flow control action will be based upon those levels. Therefore it is important that they are as accurate as possible. Sometimes as little as 2000ft difference can put you into a sector which has not planned to have you there and this may push them over the edge in terms of workload. Therefore, it would be great if you could encourage whoever files the FPLs (if they are not RPLs) to ensure that the cruise level is accurate.
This is especially true of cases where a relatively low level (e.g. FL290) may be filed and ATC or the crew then ask for a higher one (e.g. FL370) when airborne. The controllers may be trying to help but they may unwittingly overload another sector 500nm down the line.
LAC at least has advice running at the moment that ATCOs should not climb traffic above its FPL level unless absolutely necessary (weather, conflicting traffic etc).