Watching my cousin try to cut hair without clips was a mess, lol. She ended up with uneven sections because everything kept falling. Now she won't touch scissors without a pile of clips nearby.
Speed comes with practice, but clips aren't just for newbies. They keep sections neat, which actually saves time on fixes later. If someone says clips slow them down, they might not be using them right. I've seen plenty of fast stylists who swear by clips for tricky cuts. Guess it depends on whether you value speed over perfection every time.