Now, for example, easyjet flies IBZ LGW on Tuesdays in October, randomly choosing the 14th it comes in at €80 or cheaper plus bags, arriving LGW 11:00.
Then Norwegian flies direct LGW-LAX for £300 at 15:35 on the Wednesday. Depending on your budget, you could afford to stay overnight Gatwick.
There are dozens of permutations like this.