I bet it changes based on a few factors including age, prior mobility, etc. I do a few things at my current age:

  I wear Vibram "toe-shoes" so that my heel isn't lifted off the ground when I squat or do other movements and unless I'm lifting very heavy I go below parallel
  I warm up by doing either some prescribed warm-ups or by getting on the air bike/rowing for a few minutes + other warm-up activities
  I do the exact exercise movement I'm going to be doing if it's a movement like a snatch, clean and jerk, deadlift, squat, etc. to warm-up 

I don't do any stretching before or after. It's absolutely fascinating that so many different things work for so many people.

yeah your hamstrings might not be so tight, you may have different ratios in your leg bones, who knows! lots of anatomical variation