Easy way to index on a metal lathe

[Toolmaker51]

Another method is use a strip of paper or tape wrapped tightly around the chuck. Cut the paper at precisely the correct length. Layout the required divisions with it flat. Then put it back on the chuck and secure with magnets or tape.

I know this will work. Best lathes I've ever used had indexing marks on spindle nose and adjacent casting of headstock. Mainly re-positions work for multiple start threads.
Other increments there, I didn't fathom the spacing of. Perhaps for toolpost grinding of flats, without running spindle?