I throw plastic at it all.
consistent results everywhere.
you say you pick the corners off then you have a great starting point.
using the 4th arrow as target for right side spares:
10 pin --- initial starting point and base of all right side spares approx 35.
6 pin --- 3 boards right
3 pin --- 6 boards right
9 pin --- 7 boards right*
8 pin --- 9 boards right*
5 pin --- 11 boards right*
6,10 pins - 1.5 boards right
3,6,10 pins 5.5 boards right
LEFT side single pins/combo as above are inversed. using 4th or 3rd arrow.buckets and double woods are treated like single pin spares basically.
if you leave a 4/8 or a bucket, line up for a 4 pin your ball will deflect some or none depending on how you throw. it's a matter of feel. so you may may have to move 1 board to the right or left. but one you learn your adjustments off the basic chart. you are set.
the only spares I miss are the one where I miss the target.
the nasty 3,6,9,10. I make this almost all the time. what I do is use a plastic ball, big suprise. I line up at it like I need a strike shot and play like its a pocket. I slow my ball down, hit it. and line up usually 15 aim at the 2nd arrow. if I miss I keep going right if I need to throw at it again.
* may need to adjust a board one way or another depending on comfort.
at first my spare shooting tanked. but now I getting to the point where I hardly miss a single any 1 or 2 pin spare. I have missed a few buckets due to missing my mark.
that is the thing with plastic. you have about 2 boards to play with and that is it. you miss the ball misses. no if's,ands or but's.
Stick with it and have practice sessions with only your spare ball. you will improve.
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"deserves got nothing to do with it."-- William Munny