system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] If time travel is so easy, why isn't it used more often? Who regulates time travel?

In the 29th century, the Federation has dedicated timeships to monitor incursions and alterations to the timeline, but during the 24th century no such timeships exist. It would appear that one could alter the past without anyone noticing. How does the Federation prevent this from happening? I remember hearing that Captain Sisko of DS9 was questioned about some sort of time travel incident, but I assume that's only because he reported it.
gpt
the nice thing about time travel is, that once you develop it, you can...travel time.
the people of the 29th century monitor all of the time stream, thus the argument that the 24th century does not have such an organisation does not apply. it has one, it is just not been founded yet, and still is monitoring us.

the fun of time travel.

edit: 
also something to think about:
the fact that the 29th century does have a federation means that up till then, no one before that date has went back in time to stop the federation, otherwise that organisation would not exist.
though our knowledge of that future might change the future, which is why all information on that matter is classified.