Shimagnolo -
Thanks for the link - quite educational.
My technique for measuring chain wear is to use a 6" digital caliper (which I already have). If I use the inside - inside part of the caliper I can open it up to measure 6 full links. The roller diameter is nominally 0.300". So, 6" of chain minus one roller diameter should be 5.700" for a perfect (new) chain. If I use the 1% rule on 6" of chain, this is 0.06". So, a chain worn to 1% would measure 5.760".
This may not be exact per the link you posted but it is an easy way to multiply the 1% to something easily measured.
Does this sound like a reasonable approach?