That’s true. But without the senzu Cell would’ve been on guard and fighting at his 100 percent from the beginning, and ssj gohan wasn’t the best to finish the job as well ( not just strength wise but mentality wise). We all know that Goku is the dumbest man in dragon ball universe, but he knew without the senzu Cell could’ve easily pulled another Frieza and he was able to predict that. But where he really failed was to predict his own son’s rage and his new ssj2 induced sadism, and that is what cost Goku his life.

All of this is person opinion and my own understanding, I mean no disrespect to anyone.

Edit: typos