In my experience many TKs are often a frame out - it depends on the make/model of the TK suite and the format you are going to.
They hardly ever tell you this it seems...
For example the last 5 TKs I've had have been +/- 1 frame out.
All from different TK suites/companies. All big companies too!
I've never looked into it as to why - I just work round it. Maybe someone will chip in an give us a good reason!
I have a sneaky feeling it might be the TK suites without KeyKode (or Keycode) readers, but I am only guessing...
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