I assume you mean ignition coils. I would think replacement is dependent on time rather than mileage as they can last ages but then nothing lasts like it used to. So to answer your question I would say no as they are only replaced if there is an issue.
Do you say anything to the idiots riding in shorts and t-shirts or just let them get on with it??
Not being a safety nazis myself, Who am I to dictate to someone else by telling them what they should or shouldn't wear on a bike if it doesn't effect me. But who is the real idiot and who rides better? The rider wearing shorts and t-shirt that is feeling nice and cool so he/she can concentrate on their riding or the rider wearing all the right gear that can't concentrate on their riding because they are sweating their bollock off. When at work, we make sure everyone doesn't have any exposed skin and that's because of government guidelines and we have a duty of care. However, I do believe that someone not covering their self up, should have to pay their own medical expenses and not be a burden on the NHS.