My gearing is 7 speed half-step + granny, so I set the bike up to allow big-big and small-small. Around here in Flatland, I'm almost always in the middle.of the freewheel, so I almost never go into either of those gears.
Watching the TdF, I thought I saw someone (Roglic or Pogachar, IIRC) in the big-big combo, but the image was pretty fleeting, so I'm not sure.