I bought two more magazines for my VP 9, for a total of 5. I recently bought a Glock 19 but only have the three magazines that came with it. I brought both to the range the other day. Having those two extra magazines for the VP 9 makes a big difference to me. I do plan on eventually getting three more magazines for the Glock.
I also have a bag that I dump my ammo into to take with me to the range. It can hold at least 500 rounds of 9mm in it, and fits in my range bag. For me it’s much easier to reach into the bag, grab some rounds and load the magazines using the Uplula magazine loader I have than getting them out if the box.
When my friend comes with me, I easily fire twice as many rounds as he does, maybe more.