You are right that each zone has its own triac, which is rated 800mA, and that’s necessary because each zone needs to be switched independently.The power adapter does have to be beefy enough to support the number of concurrent running zones. Most people probably won’t need more than 2 to 3 simultaneously running zones, so the inrush current isn’t that much of a problem. If you do want to run many zones simultaneously, what you mentioned about staggering them makes sense. In fact, this is already implemented for remote zones — any virtual zone (including HTTP stations, RF remote station etc.) that’s scheduled to open at the same time with other zones will all be staggered with 1 second delay between each other, for the simple reason that you can’t simultaneously send out multiple HTTP or RF commands at the same time. So that staggering implementation can be easily modified to support the physical zones.