Structure sites, groups and collectors so a large network stays navigable instead of becoming one giant device list.
Keep monitoring traffic local to each site rather than polling everything across the WAN from a single central collector, see Connect Zynty to your existing network for the reasoning.
Use sites for physical location and groups for device role, so you can filter by "all core switches" across every site, not just within one.
Bulk import each site's device list rather than adding hundreds of devices by hand, see Import devices in bulk via CSV.
Route alerts to the team responsible for each site or region, not a single global channel that everyone eventually mutes.