Keep in mind,.. if your floats stick they are stuck... and having shut-off the petcock will only stop the leaking 'till you turn it back on...
Then, you'll have leaking fuel while you are on the bike...
...(same goes for the vacuum petcock)...
Do you have a preference?... while riding or parked?...
...
I only shut off the petcock if I'm parking in an enclosed space, like my shop...
Otherwise, I'd prefer to notice the puddle, rather than feel my leg soaked in fuel...
A good reminder is to hang a bandana or t-shirt sleeve over your throttle... when you turn the pet to off...