Update on our centralized system after 3 years: the single biggest maintenance item is the filter. We run 10-micron inline filters on each zone and they need checking every 6 months. Twice we've had a clogged filter starve a bearing — the system showed green (pump running, pressure OK) but the flow was restricted. Now we added flow sensors on the 4 critical points (main bearings + crank journals) — $120 each, best money we ever spent. Pressure alone doesn't tell you if grease is actually reaching the bearing.
One more thing on the centralized vs manual debate: temperature monitoring changes the equation. We put $15 thermocouple stickers on every bearing housing and do a weekly IR gun check. Takes 10 minutes for the whole press. Any bearing running more than 15°C above its neighbors gets investigated. Caught a failing eccentric bearing 3 weeks before it would have seized — the centralized system was delivering grease fine, but the bearing cage was cracking and generating heat. Manual greasing would never have caught that either, but the point is: lube system alone isn't enough, you need temperature trending too.