As every photographer knows, you use shutter speed to either blur, or freeze, motion. That is what the shutter is for, creatively speaking.
A slow shutter speed, like 1/10 second, gives you blurred motion, as in this photo I took at a country music event the other day:
While a fast shutter speed, like 1/800 second, freezes motion:
See the difference?
Q: If picture 2 was taken at 1/800 sec, why is it not darker than the first picture, which was taken at 1/10 sec? Over six stops darker?
A: Because at the same time as selecting a faster shutter speed, I selected a larger aperture: f/1.4 for the second picture, as opposed to the f/22 I used for picture 1.
Anyway. Here’s the core question I get quite often from students:
What drives the decision “do we blur or freeze?”
First, a flow looks better blurred, while something that happens as a moment in time looks better frozen. So generally speaking, for a fountain like this I would use a slow shutter speed.
What constitutes “slow”? See this excerpt from my Book 7, Pro Photography Checklists: 100 checklists, summaries, and Best Practices.
So, OK, slow or fast determines motion: blur or freeze. But there are other considerations. Like “do I want a blurred background” (which would mean a low f-number, which in turn would mean a fast shutter)? And like aesthetic considerations: the frozen fountain looks kind of cool, in this particular case.
And so it is with many photography decisions: you have a rule of thumb, a starting point; but then you interpret that creatively. That goes from everything from motion to colour to the rule of thirds. You are the creative driver, not the book or the camera or social pressure.
So if you have a reason to not use some established rule or starting point, then by all means do what you want. (In the absence of such a reason, though, go with the recommended Best Practice or Rule of Thumb.)