I challenge anybody to pass the simple CST checkering test---
Lay out a 3 1/2 to 1 diamond on flat hardwood. Assure it's accuracy with dividers and scribe the borders. Checker it to within one line of the border. Are all four sides parallel with the border?
The second test was the same thing but the wood was arched like a fore-end with a two inch radius.
The third was to checker a simple point pattern on a grip section just made as another project.
Once in a while a student came through that excelled at checkering and some even are now specialist. There was once and overly enthusiastic student that practiced checking on the toilet seat. Room mates complained.
There are no 'best' checkering tools. Different craftsmen like different tools. Some make their own. The electric checking heads that attach to Foredom tools are preferred by the very best at the art. I've seen it done with a Forediom and I've tried it several times but if I need to checker I do it with Dembart spacers and home-made deepeners.
One of the best indications of a perfect job is to look at checkering cross-wise at the shadow lines.
The first picture is of the last job by Maurice Ottmar. The second is the near in-humanly good multiple internal ribbon pattern done by Gary Goudy. To keep straight shadow lines across ribbons is VERY difficult.
Really good checkering is complete to the very last diamond with no over-runs and no line is deeper than another.