If Vegeta went back/forwards to Trunks' time to kill the androids and Cell

[Warmmedown]

Do you think he would get the job done?

 

[Captain Cadaver]

Depends at which point of the Cell Arc we're talking. Post-1st Rosat or Post-Cell Games? Prior to the Cell Games, it could go either way depending on whether he considers letting a weaker Cell absorb weaker versions of #17 and #18 is a risk worth taking for restoring his pride. After the Cell Games though, he probably wouldn't do something so reckless considering his moment of clarity in apologising to Gohan for having been a bother as well as having realised he cared for his son, so he'd just get the job done without dropping the ball.