Unless you plan on using a website for a long time, just use a temporary email address, and then this eliminates any issues that could come from that. Ideally, you wouldn't be using the same password anyway, and therefore that wouldn't be compromised. Obviously, data that you give that website could potentially be compromised, and therefore associated with your email address, which an attacker could leverage or potentially gain more information to carry out a more sophisticated attack. So, there's definitely could reason to use different emails if you do use multiple websites.

Personally, I hardly sign up to anything these days. Kind of sick of every website requiring you to give your data over by signing up.