Since you asked...
Everyone using an umbrella in a crowded theme park is a sociopath. On a very finite sidewalk, you decide that you deserve 2-3x your normal footprint? That water falling out of the sky belongs on the people around you? An extra 3 or 4 seconds waiting for you to close the thing when you come to an abrupt halt at every door is NBD for the people backing up in the rain behind you?
If you'll only use it when there is no one closer than arms reach anyway... sure, go for it. In the end, your legs and shoes will still get soaked and walking with it will probably slow you down to the point where they get even wetter.
Choose fast dry clothes, get rained on, 15 minutes later you're dry again.