No...not at all. In fact much of what people "think" about processing in Photoshop doesn't apply at all in LR & ACR because regardless of how or when you make an adjustment, the actual processing pipeline does it's own optimized processing order. In point of fact, the Contrast slider in LR with PV 2012 s a pretty important tool to use. That's why it's second after Exposure...
Forgive me for being dense, but aren't that statement and this one different? (emphasis mine)
The issue is that you are adjusting the sliders out of order, e.g., you were adjusting Highlights/Shadows even though Whites/Blacks had already been adjusted (e.g., Whites +60). The sliders are generally arranged so that the later sliders depend on the earlier ones, e.g., the range and methods used to implement Whites/Blacks depends on what you've set Highlights/Shadows to. Thus I suggest (generally) editing top-down.
Not trying to be difficult, just trying to learn and understand.