Only you can decide how much time you would like to spend volunteering. Each volunteer department varies as to how much time they need, expect, or ask of their volunteers. There are a wide variety of commitment levels available. Do a little research on your chosen team(s) so you know what their requirements are before you sign up for shifts. Plan carefully, and try not to commit to something you will not follow through on. If you sign up for one shift and show up for it, everyone is happier than if you signed up for 10 shifts and made it to six.