Stripbox: how important is a grid?

I bought 2x large PCB strip boxes. To be honest, I haven't even had a chance to use them yet. But the plan is to use them as kickers, behind and off to each side of my subject. I want to shoot some gritty sportraits with nice separation light. My question is: without grids, will there be too much spill? Or is the light from a Stripbox fairly directional? I'm just trying to understand how much more control a grid will give me and which situations those of you who own them, use them, religiously. Thanks in advance.

Oh, example photos of your work with and without would be awesome!

Thanks again

Mods: I meant to post this in studio lighting section. Can you please delete this? Thanks.

I'd always have grids available as an option for any kicker/hair/rim light modifiers, not that they always get used.