It's more often than not when I see a Reyna have her ult and just leave it there. Reyna, despite being so basic, has proven to me that with 1 ult she can 1v4 as long as she knows how to shoot properly.

When I tell a Reyna to "Just use their ult" in a 1v3 situation, they all say the same thing

"It would be a waste" which then leads me to ask myself the same question "A waste to who exactly?"

Reyna's ultimate benefits no one but herself, added to that, it's a 6 point ult which means it's considerably easy to get it back. It's an ultimate that can define the end of a round depending on the shooting skill of the Reyna.

Just use your ult man, no one cares, trust me.