So I missed my post last week - whoops! I basically didn't do anything over Christmas weekend except make it so that only the linked goal you are interacting with responds to linked goal node hits.
This week I cut out all levels that involved timers (plus one or two others that just weren't exciting me). I was basically only using timers to make different walls appear and disappear, and while that was interesting, the levels they produced didn't really pull their weight. This is sort of counter-intuitive, since this game is mostly about timing your charges correctly. But even the one timer-based level that I didn't want to cut was improved by removing the timed walls and turning them all into moving walls.
And here we have the new level, which uses three moving kill walls. The player has to interact with the kill walls in every corridor, though the far right and the far left corridors are the easiest to pass. Once you've hit the switch, you have to be mindful of where each kill wall is. You also need to account for how long your charge is going to take. The two center corridors are the trickiest to time when charging through the goal nodes.
If I had to guess, I'd say that movement is a more effective way to introduce timing-related challenges because it relies on visual information. Humans are probably just naturally better at movement-tracking than they are at internalizing an arbitrary rhythm disassociated from music.
Charging-up sound effect is by Javier Zumer. Use and Modification under this license.