Speedrunning the lighthouse lights puzzle was a NIGHTMARE. I spent hours, trying to get a good time.
My best time on amateur sleuth mode was 33.63 seconds, which equals out to getting a light every 6.726 seconds. On master sleuth mode, my best time was 47.27 seconds, which equals out to 6.75 seconds per light. Yes, I was slightly faster on amateur sleuth mode, but the time difference is pretty negligible. If you do the math, I would only save .188 seconds, if I did master sleuth mode on my optimal speed.
I am NOT going back and trying again. Getting optimal speed on randomized puzzles is rough.
To get a white light, you must make fifteen different combinations. That is, blues combine eight times, greens combing four, reds combine twice, and tri-colors combine once. So on amateur mode, you make 75 combinations. On master sleuth mode, you make 105. That's the minimum number of combinations needed. If you do the math that way, I made a combination every .4484 seconds on amateur sleuth mode, and every .45 seconds on master sleuth mode.
Amy Christine's trick of constantly doing "down, left, down, right" works relatively well. See, if you play the game like that, all the white light matches are in the bottom row. That way, they're not in the middle of the playing field, messing you up. However, that is not always the fastest way to get through the challenge. You'll definitely encounter times when it's better to go "down, left, left, down" or such.