Earlier quoted context omitted.
The 456 is the reason I stopped commuting to work before 10. Taking the L from where I live today isn't much different. The trick I've found is that if the sign says there are two trains incoming that are within a minute of each other, always take the second train. People will self-sardine themselves on the first and the second with be mostly empty.
This doesn't always work. In my experience, if you're near peak crowding areas during rush hour, the next train is usually just as packed as the first. And then the next. And the next. So you've just watched 3 trains go by that you couldn't even fit on if you tried and you've been waiting about 5 minutes. God forbid they get delayed, even for 2 minutes more. I usually just try to cut my losses and shove in as soon as…
In my estimation, shoving onto the train just wasn't worth it. It makes the ride much more miserable for people in the car, and it delays the line even more. The second point is important; the train situation isn't going to get better by people being selfish and gaining a few extra minutes at the expense of everyone else's.
More often than not, the "second train" strategy works wonders. I found that when it doesn't, I'd have to wait for multiple trains anyway. Maybe once in 7 years did I skip a train with room and get punished for it.