Hmm...so its bad to drive from Tagaytay to Sta Rosa on neutral, all the way? Since downhill sya. I did that maybe 4x na in a span of 2 years.
I did Tagaytay - Batangas (Starting from the subdivision w/ wall fountains sa labas going to Punta Fuego) Yun nice road dun. All downhill too.

Speed is 60 - 100kph on the Tagaytay to Batangas stretch,
60kph on tagaytay to Sta Rosa stretch. Both 20kms easy. Neutral lng ha.

No tranny damage, total mileage 50,000km na.

Yes, even on manuals, I'm a neutral driver basta downhill at di matao. Sanay na.