According to the A359 flight operations manual I’ve been using, there is no requirement for the use of slats (flaps setting 1) up to 10,000ft – it simply recommends that these are used for holding and/or approach, and that flaps settings 1 + F could be used for takeoff.
Your usage of flaps and slats during your flight will mainly be dependent on your weight – hence why the flight manual I use specifies three possible flap configurations for takeoff (flaps 1+F, flaps 2, or flaps 3).
Here’s my guide to A359 flap usage from my manual I’ve been citing:
||1 (Slats Only)
||1 + F
||3 + S
My flaps usage usually depends on the weight of my aircraft, and I’ll usually work out what settings I’ll use before I depart, depending on weight and what speeds I’ll be flying at before I depart – but I don’t think I’ll ever find myself in a situation where I’ll need to be using slats up to FL100 at 255KIAS – that seems unlikely!
Hope this helps.