Question the advice you're getting both now and in the future.
That having been said, I'm not sure what planet your "mentor" learned to bowl on, but I've never heard about wiping the ball adding heat to it. I wipe my ball between shots because I want to limit carrydown and maintain a consistent reaction in the midlane. IOW, I want the ball to react the same each time I throw it, therefore I wipe it clean before every shot. When I do wipe the ball I use a microfiber towel and I wipe perpendicular to the "bowtie" flare track. This pushes any residual oil out of the track area of the ball so I get a little better response.
The reason you leave high-hit spare attempts in later games is probably because you are getting tired, not because of extra heat in your ball. To counteract tiredness, add a little speed to your shot, move a little deeper and give the ball more room, or practice in longer blocks than your competitive sessions will require. When I bowl a PBA event, it's an 8 game block. Before I go, I practice in 10-12 game blocks. The last thing I need is problems with being tired in the 6th-8th games.
I think kmitch pretty much handled the corner-pins question you had. I'll just say that unless your "mentor" shoots his spares that way, he is just jerking you around.
Suffice it to say, your pseudo-coach is not trying to help you. He is playing an offensive mind-game with you to get you thinking about the wrong stuff in order to screw you up. It's why he disappeared when you shot 242 at him.
Good bowling.
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NutAnd there were in the same country shepherds abiding in the field, keeping watch over their flock by night. And, lo, the angel of the Lord came upon them, and the glory of the Lord shone round about them: and they were sore afraid. And the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people. For unto you is born this day in the city of David a Saviour, which is Christ the Lord. And this shall be a sign unto you; Ye shall find the babe wrapped in swaddling clothes, lying in a manger. And suddenly there was with the angel a multitude of the heavenly host praising God, and saying, Glory to God in the highest, and on earth peace, good will toward men.
Luke 2:8-14