Ippus
some of the differing advice may be for boards cut with different ring orientations, ie flat vs edge ringed.
often, there are assumptions made about grain, that may or may not be useful from looking at the ring orientation. true grain is laid down in each annual ring, and is distinct from the previous years growth, so if the rings are violated on a flat sawn board, the grain is most assuredly violated also. But this does not mean that a nice straight ring line on a flat sawn board does not have the dreaded spiral grain you mentioned.
its confusing because many descriptions use the word grain when they mean rings.
the short lines commonly called rays can tell you a lot about grain also. note the diagonal rays in the board on the left below
