system
Given the following post, respond as if you're commenting on Reddit:
human
[Dragon Ball] Cell can sense ki. Why doesn't he ever try to reach the Lookout?

Cell has shown the ability to sense ki multiple times (most notably to track down 17 and 18 when Piccolo is fighting 17), yet he never uses this to reach Kami's place. He expresses to Trunks after Grade 3 Trunks loses to Cell that he's curious as to how Trunks and Vegeta got so much stronger in a short period of time. He definitely would have felt Goku testing his power to Karin after just coming out of the Room Of Spirit And Time, so why does he just ignore the Lookout? The moment Buu could sense ki, he flies straight there.

The only real reason I can think of is the moment Cell arrives in the original timeline, he is preoccupied completely with absorbing 17 and 18. Once he does so, he constructs the Cell Games to test his strength, and even encourages the Saiyans to train again for ten days. But I would think he would be at least a little bit curious as to how they get so strong so quickly, and he definitely has the means to find out.
gpt
Given that Cell is an amalgamation of the Z fighters DNA, he's inherited a lot of their strengths, but also weaknesses. His major fatal flaw was his pride/confidence in his own superiority (Thanks Vegeta).  Despite his minor curiosity, he just didn't care enough to really look into it. In his mind, he's the perfect being and no one could EVER stand a chance against him.  So why would he go through the trouble of sneaking a peak at their training?  Plus, he had other Cell things to do, like flexing and stuff, probably.