I'm working specifically on springs now at 4 months into playing the game.
When moving from right to left, I use the traditional means - look for a "short" spring on DK's right foot (his right foot). Proceed to let that spring begin to go over mario's head as I move to the left and to the safe spot near the yellow area.
Then, I go "off the reservation." Tradition tells me to wait for one extra-"long" spring, let it pass over mario's head as I proceed toward the ladder... If the next spring is long, head back to the safe spot.
I stopped doing the tradition when I realized that my brain was unable to process the position of a long second spring before I could react.
SO last night I save stated through about 200 attempts from L=04 through L=10 elevator boards. In my play, looking at the left edge of the screen as the springs enter was the way to go for me. As it turns out, all short springs enter higher on the left edge of the screen and all long springs enter lower on the left edge of the screen. The longest spring enters at a low point on the left edge of the screen that can look startling in comparison to others. This is the spring I go right on. In the 200 attempts, I did not need to check the next spring. I made it up the ladder just fine provided that I started in the absolute rightmost position I could. Weird, but I plan on running about 1K attempts and at some point I will capture footage from MAME and check it.
Waiting for the safest spring is of course not ideal for scoring, so there's more work I need to do in order to not kill the bonus.