Can someone explain Dish Turbo (variable bitrate encoding)?

[gadgtfreek]

Because I like to understand things, I have a few questions.

My wife and I record a lot of stuff, so I get plenty of eval. time, and have a fairly decent sized screen/low view distance so compression issues are easily noticed. What Ive been experiencing since I came back to Dish in Nov '12, is that one week a show can look pretty good, next week, problems. Take Magic City on Starz for example. Last couple of weeks have looked pretty darn good, just watched the series finale and it was cursed with lots of banding (night scenes always show compression problems if there are any) and softness. Now I'm watching the series premiere of Hell on Wheels and it looks pretty damn good. Granted I understand they may not be on the same TP, just giving an example.

• I assume, the variance from one week to the next is based solely on TP load at that particular showing, which of course could vary?
• Dish is probably running close to the edge with 7 and 8 channels on one TP, so I imagine their is little room for error?
• Do they monitor channel averages and shuffle them around to try and get the best balance (not putting 7 or 8 bitrate hogs on the same TP together)?

Thanks, just trying to understand it more. Im a little OCD about image quality so knowing the answer always helps.