Placing your record on a spinning turntable.

Never bought into that. Why take a chance?

"I have a VPI table with Umami Red cart and a felt top."

GASP! You must be one of those weight/mat users... bare platter/clamp & washer to flatten LP for my VPI.

If you want to play radio DJ, keep spinning. I used to do it with a Rega. The only thing I can think of is a constantly spinning platter potentially leading to a disaster-lifting the LP of the platter, a hand a finger brushes against it, causing hand jerk which then crashes into arm/cartridge and you now have a new Audiogon thread subject-

"Don't keep platter spinning while changing LP's."

Why oh why?

I've been changing spinning records for over fifty years with no issues whatsoever. Motors don't like being shut off and on again over and over. So what' the harm?

Dan

While it is not the norm. I have certainly done it in the past. Typically with the VPI turntable I had for twenty years. Since the platter / motor has so much momentum it is a pain to wait to stop it. I also have 2,000 albums, most in pristine condition still. 
 

I now have a Linn. The table stops rotating quickly. So, I have not been inclined to do it. 

Just for fun I ran the question through a couple AIs. The output was not at all convincing to me that it could produce any harm. It really requires some mental gymnastics to come up with farfetched reasons not to. 
 

I would definitely continue the practice. Life is too short to waste time. 
 

I can't imagine it being a problem as long as you keep using that felt mat on top of the platter. I wouldn't do what's being described with an acrylic or other hard material for fear of the micro scratches that would be the almost certain result.

NO, NO, NO

Aren't you using a center weight?

My JVC TT81 (many of their models) has a start/stop while powered on.

My old Thorens TD124

had a 9lb cast iron main platter that kept on spinning, while you lifted with a lever, an overlay thin platter that stopped spinning, change the lp, then drop the lightweight platter down onto the 9 lb platter. Instant start, method for radio stations  who probably had two setup and an emergency spare.