How bad is cross chaining? Accepted wisdom is that cross chaining is bad and that we should never do it. However, most of us set up our bikes so that we can run any gear combination. Invariably, I'll occasionally look down and see that I'm running my big chainring against one of the bigger cogs.

Is there any measurement of how much faster equipment will wear out from cross chaining, or energy loss or whatever?
The only study I know of concluded that cross chaining in relatively modern 9spd gear systems at the angles typical of bicycles had no measurable effect on the efficiency of the gearing system. 

Even back in the bad old days of 52/42 with five cogs in the back, I never worried about cross chaining. Use the gears you like and replace the chain when it starts to show wear and your relatively expensive cogsets will last a very long time. 

Riding with a worn chain destroys gears, not cross chaining.