I was recently watching videos of the world Marblehead championships in Italy and the recent pre European regatta in Torrevieja in Spain. All the fleets exhibited the same behaviour with boats lined up well before the gun sitting stationary on the start line. Get the start slightly wrong and you are buried. Get it right and you can sail fast and be tactically free.
I cover the start in the web site but I cannot emphasise how important it is to develop the skill of keeping the boat stationary in one spot and be able to manoeuvre it slowly to keep your position. So many times you see someone ruin their start (and sometimes others) because they over sheeted and shot the boat forward and out of position. I know as I have done it myself.
This skill is required for any crowded start, e.g. ranking event or the nationals, or any international event
Here is an example from the m worlds
Seems a strange thing to do to practice stationary sailing but it is well worth the time and effort to understand how the boat behaves standing still and how long it takes to get up to speed.