Here's an example of needing to go "early".

I have an 1145 flight. I have a 1000-1030 meeting where I need my laptop in front of me.

Normally 1000-1030 would be right around the time I'm clearing security. My trip the airport is less than 30 minutes, so I can't do it from the car.

That means I either leave home at 1035 (I've done worse, but that's pushing it), or I leave home in the next 15 minutes, to ensure I'm in the MLL by 0955.

I don't really want to be in the MLL for 90 minutes, but it's the most reasonable option.

If I also had a meeting from 0900-0930, I'd be pushing the 3 hour limit.