In the world of iPhones all the average consumer is getting every year is bigger stats rather than new toys. If you upgraded from the 11 to the 15 you’d get some nice-to-haves granted but nothing that is going to magically upend your life.

I would run the 11 into the ground and only bother to change it when the battery life becomes anxiety-inducing or Apple release a product with an idea that you buy into.