Thanks, Ben ~
I appreciate both the clarity and the reassurance that no matter what timer-advance increment any given model happens to have, the operator enjoys 144 or 200 seconds of 12 jet circle spray,
a boatload of water either way, making for extravagant and sensational spray rinsing, one of the secrets to the GM 1-18's exemplary performance.
I've made the contact, receiving my first, huge, powder-blue Facebook Marketplace thumbs-up icon a few days ago, nothing however since; will keep you posted.