Yes I always fold my slice when I eat pizza! I find it hard to eat pizza unfolded, it’s too big to fit into my mouth! I have done it in front of out-of-towners and they told me it’s a New York thing.
It depends if I have a plain slice or one with toppings. If it’s plain, then yes, I fold it. If there are toppings, I find that folding it makes the toppings fall off, so I keep it straight.
dafyomi-Yes I wash and bench even on one slice, but I hardly ever meet anybody else who does, and every time I tell somebody that I wash on pizza they think I am crazy.