Record clamp/weight and turntable speed

@mijostyn  I did indeed download the RPM app and discovered my main VPI HW-19 tt runs around 33.64, while my Craigslist marketplace let-the-kids-use-a-turntable TT runs around 33.17.

Without a dedicated clocking device, do all tt's vary in their speeds like this?
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Thank you both for your answers, topical and metaphorical both. they both help out, especially the one about the turntable platter getting up to speed, no matter what the weight.

@lewm I provided no info because I needed no solution. I was just curious about whether a record clamp affected speed or not? My clamp is a VPI screw on clamp which I loosely tighten, though not overboard.

I have the Herbie's mat now. Without a clamp, the warped records (those I have) tend to skew the sound. 

Oh, and while we're on the topic of record clamps, what justifies the Shun Mooks $5,000 record clamp? 

The Herbie's mat has a white washer you fit on the spindle on top of the mat. That takes care of any center depression on the platter

@bdp24 Yeah. That's what I have.

@xaak - My Herbie's Mat has a rubber washer between the platter and record. What does that do for the physics of clamping?

@xaak. I run a VPI HW-19 Mk4 with a screw on clamp. The Herbie's mat washer rises about 2-3 mm above the mat. The VPI platter has a concavity which matches up nicely with the Herbie's. Thank you for explaining the reasons behind that!