If you are lucky, your center hangs out an oil graph - it will tell you how long the oil is, how it is generally distributed and how much is applied. These are the most important figures.
If you have to guess, things become tricky. Normally, you won't be able to see or tell what's out there - at least from the approach. Sometimes you are lucky and yo can see dry outside boards, and the amount of oil at the foul line might indicate the oil amount/depth - but this is already guessing, since you cannot tell what's going on behind the arrows.
Sometimes you are lucky and can walk up the side of a lane - from the side angle it is pretty easy to "see" the oil pattern and its length.
If you do not have this option, some test shots with a fingertip reactive can tell you a lot:
Play straight down 10th board and watch what the ball does, when it changes direction and how it finishes. Without a buffed zone, the ball will grip when it hits the dry and change its motion - this way you can tell how long the oil is, and how much grip the back end yields. Depending where the ball hits the pins you can then make feet and target adjustments to move towards the pocket, and you can tell if you have to stay straight or can try to swing the ball.
When the ball comes back, watch the oil rings: are they a few or many, are they big or small? This will, with some experience, also tell you a lot about pattern length and volume, and how to quickly adjust your game.
With this you won't be able to scout the pattern in detail, but with some training you should be able to guesstimate what's out there and which path to the pocket should be effective. But there's no guarantee, and you will have to keep your eye on the ball's reaction just to anticipate lane changes over time.
Hope this helps a bit.
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DizzyFugu - Reporting from Germany
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