i use this to practice doubles on 3,8,10,13,14,20 but for this regimen you'll run through all 20 wedges.
the game focuses on putting 3 darts in every double to close it. close = 1 point. however, say first dart scores d10, second hits s10, you can still close the wedge and score a point if you hit DB with your third dart. Likewise, say you hit s10 with first dart, you can still close with DB on second and double on third OR if you score treble with 2nd AND 3rd dart. Any hit outside the wedge or DB voids the point for that wedge. max score is 20.
example
s1, db,d1=1 point
d2, s2, db=1point
s3, t3, t3=1point
d4, d4,s4=0 point
d5, d5, d20=0 point
s6,db, miss=0 point
