Given how much iPhones cost, the average person will protect their investment as much as they can. Ironically, as the cost goes up for newer iPhones the fragility also goes up. Because they are being designed with bezel-less screens and integrating more glass, they are less durable. So, you may not want to remove your protective case under any circumstance. Yet, several armbands will require you to do so to achieve an ideal fit. This will not always be the case, clearly, but it is not uncommon for armbands to require a slim case. Given that most armbands come with a screen protector for your smartphone and secure it in place, it is not too much of a risk, though.