When scaling on object level you need to keep in mind that the scale factor is inhibited by any children hierarchy linked to it, which is especially problematic with animations and non-uniform scaling but generally with anything further down the road - controllers, procedural map scaling, modifiers etc. Let's say you scale a plane to 25%, that way units in modifiers (for example shell thickness) is also 25% of what the value actually is (so now, 10 mm in the modifier become 2,5mm in actual thickness on the plane).
When scaling, either scale in sub-object mode or use an XForm modifier, that way scale on object level still remains 100%.
