Bridge Tip # 14
It is easy to conprehend if you realize each of your long trumps will probably be equivalent to aces if you play the contract in that suit. If you have length in your partner’s suit there is a good chance your partner will be able to ruff a suit in a suit you have shortness gaining one or more extra tricks. If that doesn’t eventuate your length helps to obviate bad breaks in the suit or may help partner execute a strip and endplay.
The old Goren books told you to add points for length for a supported suit and told you to add more points for an outside singleton or void if you and your parner had found a fit so this idea is hardly original to me.