Record clamp/weight and turntable speed

Hey all. So today I thought for the first time if having a substantial weight or clamp on the spindle affects the platter rotation speed. It doesn't for me, as far as I can tell, but if not, why would that be so?

It can happen ONLY with belt drive turntable!

For Direct Drive this problem is irrelevant and not exist even with high mass platter mat + heavy record weight or clamp. 

This is by far the best clamp/weight I even owned!  

@mijostyn  The “sound” of a turntable drive is BS, you hear the sound of cartridge/tonearm mainly. The rest is speculations. Speed must be stable, period.
Even very cheap direct drive can’t be affected by the weight of a record clamp.
Not every Direct Drive have a high torque and immediate start at constant speed. Not every DD have a high mass platter. My luxman pd-444 or Victor TT-101 are not high torque turntables.
Technics is a high torque turntable, even if you put 3kg on the platter the rotation will be stable with immediate start!
Belt drive can be affected by many factors and the speed is the main issue, read tons of comments on audiogon from BD turntable owners, those type of drive is notorius for not stable rotation. Most of BD turntables on the market is junk and people love it!

@chakster    3kg???  Many TTs have platters weighing 25kg, some much more. Over-engineered glitzy TTs with extra bling are one of my pet hates.

I’m talking about additional platter mat and additional record weight, not about stock platter weight. 
Some modern belt drive weight a ton, looks like a bunch of heavymetal, cost like a house and still ugly as hell. This is what you’re talking about? 
A mass market belt drive turntables are very light and if you will put 3kg in the platter you will burn the motor probably. 
The weight of additional platter or clamp is irrelevant for Technics direct drive, no harm for the bearings and everyone knows it. Been using SP-10mk2 with Micro Seiki CU-500 mat and ST-10 weight (about 4 kg additional weight all together). Still immediate start with Technics DD motor. New SP-10R is even better!