First, let me explain the syntax I've used above. REPEAT/CHAIN/(IM)PULSE should be self explaining. The commands following are what's in the cmd block. Indent of a block means that it's chaining from previous.
BLOCK means it is conditional on the previous block in the chain.
The test score is the number of ticks between pulses. You could make it a score of its own for on-the-fly editing. !IMPORTANT! Make sure that the IMPULSE block is {auto:0b} when you leave it, otherwise it won't trigger again (as it's an impulse.)
I think as an idiom, if line is meant to be pulsed once, then rest a number of ticks, then it should be pulsed by an IMPULSE.