The Terminator series plays hard and fast with time paradoxes and the like. However the answers to the question "What does a Terminator do once its mission is accomplished?" suggest that in each movie the Terminators get a little bit smarter.
For example, look at the mission parameters of each 'evil' terminator:
From: Skynet To: T-800 Subject: Kill Sarah Connor Kill Sarah Connor, she's in LA. Maybe just kill all Sarah Connors. You are just too dumb to know if it's the right one, so kill them all.
From: Skynet To: T-1000 Subject: Kill John Connor Kill John Connor, he's in LA and lives with this foster family. Also, the last guy messed up, so Sarah is still there and she is pissed. Maybe see if you can find the guy who made me. She might want to kill him if she finds out I'm trying to kill her son.
From: Skynet To: T-X Subject: Kill Mr and Mrs John Connor Attachments: list_of_resistance_dicks_and_their_locations.xls Kill John Connor, we think he's in LA, but can't be sure. The last two guys messed up, so he's in hiding, so please try and find him. Oh and kill him. But hey if you can't find him that's cool, I've attached a list of his lackeys. Just kill them until he shows up. PS: Don't worry about Sarah, she's dead LOL. Puny humans, am I right?
As we can see, the mission parameters for each successive Terminator gets smarter with more scope for interpretation.
Is there anything to support the idea that each terminator adds more technology into the timeline that makes building terminators easier, or smarter?
For instance, in Terminator 2, Miles was impressed with the technology of The T-800 from Terminator 1, suggesting that he'd not seen this kind of tech, that made developing further tech even easier, leading to smarter robots sooner, leading to the more intelligent T-800 that saves John in Terminator 2, and so on.