Time Travel/Analysis

Required Secondary Powers
Most time-traveling heroes have the benefit of being immune to Temporal Paradox and the physical effects of The Time Traveller's Dilemma. Even if they do accidentally erase their own parents from history or create an even worse Crapsack World by killing Hitler only to have someone worse take over, the hero will remain unchanged and still be capable of trying to Set Right What Once Went Wrong.

There's also the problem of traveling only through time and ending up floating in space because surprise, surprise, planets, star systems, and even galaxies happen to move around. Most time travel stories will completely ignore this problem, so the auto-compensation is a Required Secondary Power. Some time machines even teleport to a different place on Earth relative to their starting point, which just happens to be the perfect spot to set the plot rolling, with no specific input from the travelers to go there. There is also the issue of traveling too long. If you're gone for six years, you can't come home on the day you left and expect that nobody notices that you're six years older (you can always tell them you went to California to have your face lowered).
 * The short version is that, if you kept inertia, you would move through space- but you'd wind up nowhere near your planet anyway. The long version is that the time traveler would, unless the time control device had some sort of "Non-relativistic inertial dampener" built in (which would arguably be worse) or had the prerequisite auto-corrector, maintain their current heading and velocity through space at the time they leaped. Unfortunately, this would not take into account changes to the planet's velocity (as often happens, altered subtly by potential events like the gravity of other celestial bodies, meteors or very large explosions) between departure and arrival. However, this is further complicated by one main factor- your velocity being more or less perpendicular to the planet's actual travel path due to planetary spin. Your chances are... bad if you try to jump to the future. You're definitely not making it if you attempt to travel backwards through time under these conditions.
 * Note that these are only problems if the traveler jumps immediately from the departure time to the arrival time without existing in the time in between. If instead, the traveler could change the way time affects him, (such as speeding up time to go to the future or reversing time to go the past), any forces that would affect the rotation of the planet would affect him as well. However, this also has many of the same problems as Time Freezing.