system
Given the following post, respond as if you're commenting on Reddit:
human
[Dr. Who] Most of the Doctor's problems could be solved by showing up somewhere a week earlier with more knowledge of the situation.  Why doesn't he do this?

He was sad that he had missed Madame de Pompadour, since she had died before he made it through the fireplace.  If only he had some method for traveling through time and space.
gpt
Once the Doctor has become involved in events, he can't go back and rewrite his own time line. Think back to the episode Father's Day: that's what happens when a time-traveler takes an action that invalidates previous actions from that same time-traveler. Now, using a vortex manipulator gives you a little more wiggle room, but those things are dangerous and should only be used when the universe is already falling apart.