It all depends really on whether you feel the cars around you have noticed you.
When the traffic has stopped, almost stopped then I'll take the most care, possibly only 10-15mph more, as it's then that the ignorant b&stards don't use mirrors etc.
I usually commute at around 85mph, 70mph is when I start thinking about filtering past if the traffics backing up, or if I just want to get past some real annoying twat.
But always I make sure I think the other people around me have seen what I'm doing.
'The great fallacy is that the game is first and last about winning. It's nothing of the kind. The game is about glory. It's about doing things in style, with a flourish, about going out and beating the other lot, not waiting for them to die of boredom.'