system
Given the following post, respond as if you're commenting on Reddit:
human
[Terminator movies] In timeline 1, did Skynet send multiple terminators back at the same moment?

Take Sarah's perspective. A T800 comes back to kill her and fails. Presumably, Skynet realizes that since they aren't in a winning position after having sent the T800 back in time that it failed. So how long did they wait to send back the T1000? And the T/X? And why not send multiple terminators to the same time? Sarah perceives years in between each terminator's visit, but was that the case from Skynet's perspective?
gpt
They're separate Skynets.

Skynet 1.0 was developed by Cyberdyne Systems. It went online in 1997 and brought about Judgement Day. In 2029, it sent a T-800 back to 1984 to kill Sarah. The Resistance captured the time machine, sent Kyle Reese back to stop the Terminator. Mission was a success, timeline was preserved.

Unfortunately, Cyberdyne reverse-engineered the Terminator's hand and gave Skynet a head start in technology. Judgement Day still happens in 1997. By the time 2029 rolls around, Skynet 2.0 developed the T-1000 prototype and sent it back to 1995 to kill John and Sarah Connor, while also sending a T-800 to 1984 to close the time loop. So if the T-1000 failed, the Skynet 2.0 will still be born. Why not send the T-1000 back to 1984? If it failed, there is no guarantee that the new Skynet will arise.

The T-1000 failed, Cyberdyne is blown up, John survives. Unfortunately, Skynet 3.0 was born due to the US Department of Defense taking Cyberdyne's contracts and giving them to Cyber Research Systems. Judgement Day was pushed back to 2004. In this new future, a T-850 managed to kill future John Connor in 2032. This time, Skynet sent back the T-800 to 1984 and the T-1000 to 1995 to close those time loops, and the T-X to 2004. Skynet is learning from its past failures and set up a few contingencies, targeting John Connor's future lieutenants, and infecting the present with a Skynet virus to ensure its survival. 

Once again, the Resistance captured the time machine, sent back Kyle to 1984, the T-800 to 1995, and the T-850 who killed adult John to 2004. Why not send all of them to stop the original Terminator in 1984? Because by now the Resistance realizes that everything they have done so far only succeeded in delaying Judgement Day. Even stopping the Terminators and destroying Cyberdyne only ensured that Skynet will be created by someone else. Messing about with those earlier time loops may erase their progress and bring about Judgement Day much earlier.