Do I have to rinse deep conditioner out on the same day?

I like to shampoo, then deep condition, but I'm too lazy to get back in the shower again to wash it out - also deep conditioner gives me great curl definition. So I leave my conditioner in, wear it like a wash and go all day, then rinse it out in the evening after I work out, or even the next morning. However, I've seen some people say you shouldn't leave deep conditioner in for too long - is it really a problem? I have shoulder length (mainly) 3c hair.