I'm the complete opposite - I always err on the early side. On Saturday, this ended up as being landside at T5 at 10am for a scheduled 1325 flight (delayed until just after 1400). To be fair, the M25 was a dream and we walked straight onto a car park bus.
Given the vast majority of my flights are to GLA or DUS, I've probably spent twice as much time in airport lounges than actually in the air over the past 12 months. And given I'm on the perpetually delayed mega-late 2145 LGW-GLA this Friday, I'll be warping that stat even more no doubt this weekend