While watching the United States Grand Prix a number of things frustrated me, first on the list being McLaren.
Jenson Button failed to escape Q1. As he said, it's a team effort, so let's just have a look at what it tells us about the team.
The fastest lap in that phase of qualifying was a 1m36.2s, so to that you add your own estimated warm-up lap time, which we'll say is 1m50s. This means you do not want to leave the pits for your final run in a qualifying session until there's less than 3m26s remaining.