Having a range sight on the leeward (pin) end of a start line greatly improves your starts. The picture below shows the few seconds before the start of one of the races at the recent moth nationals.
The picture was taken from the committee boat looking down at the leeward end (a small yellow buoy to the left of the water tower.) The boat closest to the camera is sailed by Mike Parsons, who has won the nationals a number of times and who finished 2nd in this year's championship. I am sailing the white boat mid-way down the line. Note the mid-line sag caused by the boats around me having held back because they are not sure where the line is. I am using a range on the far shore to pinpoint exactly where the line is. (I had chosen the right edge of the red roof as my range.)
More on finding ranges is found
here as play #8 in Dave Dellenbaugh's Playbook Series #1
Starting Strategy and Tactics
The picture below was taken shortly after the start. Note that Mike and I are about even and the rest of the fleet is already behind due to late starts. If I remember correctly, the wind was in an oscillation that shortly backed left and I tacked to port and easily crossed Mike (and boat number 2000.) I went on to win this race.
Good starts make a big difference!