For the Roto Leagues, the number, 200, is how many total starts your pitchers can have for the season. If your team hits that number and still has starters for that day, then those starts will count, and allow you to go over 200. However, all starts after that day will not be counted.
For H2H Leagues, the limit number is usually around 10-12 starts per week. This is how many total starts your team can have for the week. Again, if you hit the limit number and still have starters for that day, then those starts will count. However, all starts after that day will not be counted.
Example for Roto: You have 199 starts on August 12. You have 4 starters scheduled for that day. All 4 will count, even though you exceeded the limit, giving you 203 for the season. You are allowed NO more starts. Even if you have starters in the active position, their stats will not count.
Example for H2H: The limit is 10, and you have 9 starts going into Sunday (assuming that Sunday is when your week ends). You have 4 starters scheduled for Sunday. All 4 will count, even though you have exceeded the limit, giving you 13 for the week. If you are in a H2H league and want to stream pitchers, Sunday (or the last day of the week) is the best day to do it.
Hope this helps.