Like so many things...
it depends. What are you going to be doing? Patient transfers? Event standby? 911 responses? First aid? If you're gonna be doing patient transfers from the nursing home to the doctors office, you probably won't be needing any shears. If on the other hand you're doing first aid at an event, you most likely will need them at some point, maybe a lot.
I work on film/ television commercial sets, I don't have a ambulance, all my equipment is carried, by me, to each job. I set up a table with my stuff, I use a small tool case with a pair of shears, a penlight, couple pairs of gloves, and a pair of bandage scissors in it on my belt. I do this because it works for me, if some of the folks on this list saw it, they'd think I was a whacker. To which I respond so what? I'm not always standing near my main supplies, occasionally something will need to be cut quickly, ie, piece of wardrobe or scenery. I use what I use because it works for me not because some anonymous folks on a web forum think that carrying a pair of shears looks bad.
I'd also add that on the rare occasion when I use my shears to cut something for a crew member if asked for help, the people who hire folks to work on their multi-million dollar budget projects like it when they see people who have the proper tools onhand and use them as needed without worrying about what others think they look like.
Find out what you'll need in the way of personal tools, try a few methods of carrying them until you find one that works for you and then use it. If someone makes fun of you over it, it says a helluva more about them than it does about you. If you don't need em, don't get em. Doesn't get any simpler than that.
John E