Initialised at the right time, this can prove devastating - the underlinks effectively put Seven Sisters a level below the other stations, and with careful choice of targets this can lead to a massive token buildup. Being one of the Underground's three Holding Stations, it is possible to gather every game token at Seven Sisters and strile unimpeded to Mornington Crescent, regardless of LV. (ref. Halfman v Murchison, 1984; Maelberg v Amberly, 1989).
The difficulty in performing the manoeuvre is that early in the game or when in knip there will not be enough tokens in play to satisfy the full requirements of a seven-way token cascade. In these circumstances, another player can challenge with a call of premature septimus.