Correcting drifting with Sutherland Timeline

Just had a couple of days setting t/t speed using my newest purchase - the Sutherland Timeline Laser timing tool and thought I would share how good it is, once I got my head around how best to set-up and use it.
The supplied one page instructions are vague to say the least and it took me time to settle on which wall I was looking at to see the laser projection settle.
But once I got that fixed, it was easy to make minute adjustments on the VPI SDS and easy to correct drift and pitch. I found that using a sheet of graph paper 'blue-tacked' onto the wall behind.
Astonishing to see the effect that the addition of the periphery ring clamp to HRX platter had on RPM. Never before have I been able to recognise and so accurately use adjustment of SDS khz and hear the pitch snap in to focus.