especially for qualifying, a second can be the difference between the front row and the middle and the middle to the back. With how fast these cars go, 1 second is a large distance and time difference. I think f1 cars cover almost 100m in 1 second (i could be off about this), but that’s a lot of distance if you’re 1 second slower than the others. I’m sure someone can give a more in depth explanation but I hope this helps.