I agree with Deamon about the shots executed when the body and arm has not loosened up yet. There is a tendency to "pull" the shots or simply just a shortage of ballspeed at the release because the release will not be as clean as it should be. All this kills the length of the ball.
Too often, I see people adjusting for these "non-representative" shots and ruining the line they had or could have had. To far too many bowlers, there is only one rule:
The ball overhooks = lane too dry.
The ball underhooks = lane too oily.
I don't mind so much that these jokers kill their own game. But it's the advice that they give to others that destroys the trusting recepient's game.
About the topic, I do not have a set rule for reading lanes. I simply watch the ball move. The way the ball reacts tells me all I need to know about the lanes. The most crucial point for me is to watch the roll of the ball at the expected breakpoint. If it bites or skids tells me about the amount of oil present there or beyond.
About the sequence of practice shots, I have answered before in an old topic.
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