Any valve lash advice from the gurus?

In my experience on the slants I have had; the valve stems tends to wear grooves in the arms. I use narrow feelers that fit in the grooves. They are just regular feelers snipped to size.
I do each cylinder at TDC-compression, working thru the firing order. I marked my balancer at 120* intervals so the whole process only takes two revolutions. And I leave the plugs in, cuz the Dcr on on mine have always been so low,they are easy to turn over by hand.