Considerations for a restart
My first consideration if I want to take a restart. How long will it take? Restarting can cost you more time than you are expecting. Not only do you need to get back to the line, but you need to get high enough to start again. Which means finding a thermal that is in close proximity to your start. So just getting 5 miles back to the line won’t help because you need to find a thermal near the line climb and then go. So best case it could take you 10 min, but if the sky is cycling or a thermal is not near the start it could easily be 30 min.
Anytime I am thinking I want to take a restart I budget 20 min and determine if it is worth starting in another 20 min from now. If the sky is getting better and better then maybe a later start is a really good idea.
However, you have to think about what were the factors in determining your start in the first place? Looking at the weather you are thinking about the peak of the day and at the end of the day. You definitely do not want to be out on task when the day ends. So the weather could be increasing, and you want to restart, however, you do not want to get trapped at the end of the day because you are out on task 45 min longer than you were originally planning.
I have done a restart nearly 45 min later because the fear of cirrus moving in got me going when the gate opened, however, it was clear it was not going to be a factor and the day would be much better than forecasted.
It is generally a bad idea to try taking restarts when you are worried about the day ending or storms. You always must think about what that new start time is going to do to your finish time. At your first contest, don't play the game just get on course and try and make it around. Definitely do not try and take a restart after the start gate has closed. If you are getting too much later then the rest of the gaggle or the fast pilots. Remember a restart is going to take time to get back. You have to think about your finish time.
A good time to restart is when you miss the first thermal and get stuck, especially on an into the wind leg when it is easy to get a restart because you have been drifting back towards the start. If everyone else is groveling along with you then you might collectively all decide to just keep going. But when nearly everyone else you see floats on above you then it might be worth trying to get that restart. The first leg might be into bad air but the start is still in good air, then it could be worth the restart. However if the start is also in bad air, or it looks like the lift is going to continue being soft it might be worth it to just keep moving on.
I have many times rolled out of my pre-start thermal, crossed the line, and expected company going with me. However, they did not start. This is generally a few mile detour and head back to the gaggle. This also goes for when I head to the wrong cloud-first. I will get my mindset on where I want to head out of the start and after starting I realized that was not the best line.
Mentally it is good to feel strong about your start and your course. It is not a good start to a race when you feel you already screwed up.
I did do a restart because I did a relight. I was able to make it back to the airport and it would be faster to get a tow to 2000 ft than it would to climb there.
Do not get caught up in what everyone else is doing. Pick your start time and anything plus or minus 15 min is not a big deal. But remember what the soaring will be like at the end of the day. I have seen more people score poorly getting too late of a start than I have people increasing their score.