Also, screw killing Sarah's parents, just send another Terminator to get her in 1984 instead of giving her and her ******* kid 13 years to prepare. Idiot Machines need to upgrade their firmware.
Actually, it's not Skynet's fault really. To quote from the
RoboCop vs. The Terminator comics, "Time travel is tricky business." By the way it's suggested, there's no real way to know for certain if the time machine has pin-point accuracy when it comes to sending someone or something back in time. In
The Terminator: One Shot, it deals with a Teminator sent after a Sarah Connor who had recently moved to San Francisco from L.A., and the story is sent in the same timeframe as
The Terminator. There was another Resistance Fighter that was sent back to protect her in case if she was THE Sarah Connor, but he was sent back a few years too early, despite being sent in after Reese was. Even in
RoboCop vs. The Terminator, there's at least two noticeable times where the calculations were off that lead to the person/thing going through ending up in the wrong time (Flo tried to go back before the events of RoboCop to kill Alex Murphy and destroy his brain before he could be murdered and then turned into RoboCop, but somehow ended up after he became RoboCop. The other time was Skynet trying to send a machine back before RoboCop was developed so that the technology could be exploited to insure that Skynet ended up being developed. It went back early in time all right, with an unexpected end result). In fact, there's evidence in the films that show this happens, as the T-800 Terminator sent back by John in
T2 well after the T-1000 was sent back ended up arriving shortly before the T-1000 arrived.
In fact, I have reason to suspect that the T-1000 (the advanced prototype) was the first one sent back in time and programmed to kill John Connor. But when Skynet noticed that it didn't succeed in its mission, it sent a T-800 further back in time as a backup, unaware that it failed too before Connor and the Resistance destroyed Skynet. Since John knew that Reese was his father and remembered the events in T2 (if you don't include T3 and TS), John purposefully sent Reese back in time and then remembered to send a reprogrammed T-800 back after the T-1000.
Basically, the T-1000 was first, then the T-800 was second, followed by Reese and the reprogrammed T-800.
"Time travel is tricky business." Even a machine like Skynet wouldn't be able to make sure it got it right.
For T1 it doesn't matter, as that is the only time: paraphrasing - "no one else comes through, it's just him and me". Pretty much negates all the sequels right there.
Well, for T1 and T2, it still works. You see, John may have told Reese they were going to destroy the complex after he was sent through, but it may have been before John discovered the T-1000 was sent through. After Reese went through, John discovers the T-1000 was sent through, thus leading him to reprogram a T-800 and sent it through as well. After they were sent through, the complex was destroyed (I'm not including T3 and TS in the mix).