It's not my favorite thing but honestly sometimes it's helpful and I allow it to relieve some of the pressure that i'm feeling to get the words out. However, I do always finish my words, but I definitely use them finishing it for me as a springboard to help me get it out. It doesn't happen to me very often, especially with people I don't know and not even very often with friends or coworkers. If someone is being patient with you, respect that patience and show gratitude for it by being patient with yourself and your speech. Anger is the main emotion i feel when I stutter as well, but it only ever makes it worse. Be kind to yourself. (So much easier said than done. I know)