It is useful to make this higher than ttt_preptime_seconds so that players do not have to sit out a round just because they loaded slightly too slowly. The length of the preparation phase for only the first round after a map loads. The length of the preparation phase that occurs after players spawn in and before traitors are selected and a new round begins. Round structure Preparation and post-round
You can always view the current value on your server by simply typing only the name in the server console and pressing enter. The default value of each convar is listed for reference. You can find those in-game in the F1 menu. The below is a listing of settings servers can configure in their server.cfg (or similar) to customize the gamemode.
