Not the best option, CO. I can tell you from experience. You need to be able to hold that thing on your shoulder, no matter what, and the use of the arm from which it depends is, therefore, restricted. If the bag is lain aside, you're risking having it stolen or out of reach.
The young lady has the right idea - you need to wear it on you - but her routine is complicated by her clothing choices. We older ladies are less restricted because our clothing is less restricting.