Weak Jump shifs

In standard SAYC a jump shift response to an opening bid of one of a suit shows 17+ HCP., but, in practice, it is rarely used and when it is there are other ways to bid these types of hand hand (especially if you play 2/1 GF).... So , increasingly, competitive players tend to use Jump shifts to show a long (6+ cards) weak (2-5HCP at level 2, 3-7HCP at level 3) suit, inviting the opener to pass and play a part-score in that suit, except if he is maximum and fitted...