Try and get hold of a Nova test strip maker. I don't know whether they're still available. They are made from two pieces of perspex joined by a hinge. The top piece has a window cutout. The edge of the printer is serrated in such a way so that the edge of a piece of 10 x 4 paper is exposed, so that you can move the paper down the test strip maker.
You set the timer to make separate test strips and place the maker so that the window is positioned on the baseboard to expose an important part of the image.
The advantage of this device is that you get the same area of the print exposed for each test print: especially useful for identifying the optimum print time for tricky highlights.

FWIW, I rarely have problems distinguishing between 1/6 stop test strips. Do you have a bright enough white light in your darkroom?

HTH