The example I always use is the 1996 Elite Men's NCNCA (that is, Northern California Nevada) District Championship 40km TT. NCNCA is pretty competitive.

PLACE TIME NAME
-- ------- -------------------
1 52:56.3 DAVID LELAND
2 52:57.1 ANTHONY CRUZ
3 52:57.8 DAVID BAILEY
4 52:58.1 TIM GRANSHAW
5 53:00.9 GRAHAM SIMPSON

Not only did Granshaw lose a podium spot by 0.3 seconds overall over 40km -- if he'd been .05 sec/km faster he'd've won the whole damn thing. That's 1/20th of a second per km, and 1/20th of a second is literally the blink of an eye. That was the difference between winning and not standing anywhere on the podium and a long quiet drive home.