I love doing it, I do it almost everyday for a minute or so.
I used to be much of a grower and my erection turned rock hard extremely quickly so it was somewhat rare that I was able to do that in my early 20s, perhaps just after fucking and to the amusement of some girlfriend.
But now I'm much of a shower and my flaccid 5.5~6 inches look very fine for this. I think it may even stretch to full erection length (8 in) with the centrifugal force lol. It doesn't look as spectacular as
@Mr_Snufalufagus over there but you get the idea.
I think it may work very nice for improving your grower size into more of a shower, as you're accustoming your dick to be comfortable in a semi-hard state. Speaking of showers, I love cold showers and I've started doing it under the cold, and somewhat it's like the cock and balls get accustomed to the cold water and don't shrink as much as they used to in the same situation.
And on topic with OP, I love to do that in the wild, subtly at least.

I have practiced the motion just so I can spring here and there a bit of it, perhaps when I get my dick out in the wild to piss or before I put it back in my pants, or how to do subtly at the locker room when undressing. If you are already semi-hard it can make any average cock look much heavier and spectacular.
And if you're considering recording a video, try recording it in slow-motion or playing it slower with a video editor because that's were the fun is, I've tried that with my own and it's hypnotic!
