flaps/slats

Well again, (see the descending post), Below 10000 feet the pilot is limited to 250 knots, or whatever the controller tells him/her. The required position of flaps depends on aircraft weight, airspeed, OAT (outside air temp).
That's it! ...rob

On departure in an airline (generally) 1500ft AGL is flap retraction height. At this height we would select 250kts the nose lowers to a more gentle climb attitude and flaps/slats are retracted on schedule. Drag costs $ or £! So the sooner they are retracted on departure or the longer they are stowed on approach the better for the beancounters!

In most airliners it is unsafe to fly slower than 200kts without extending the slats. This is due to the wings being swept. The slats prevent the tips of the wings from stalling thus maintaining roll control. Drag does'nt become much of an issue until the flaps are extended more than 20 degrees. On one flight from CMH to DFW in an MD-80 I observed 3 flap retractions during climb out. We leveled at 7000' for a short time, we must have been at around 200kts because the slats were still out. We also needed to do a 180 deg turn in order to get on the right flight path. A turn at 200kts vs 250 kts takes a good bit less space to do. After the turn was complete the pilot throttled up, accelerated, pulled in the slats- I assume at 220kts or better and started to climb again. In the flap schedule, the slats are the first thing to come out on descent, and the last to retract during the climb.