Typical ZWave Neighbor Network

My Z-Wave network has been lackluster from the start (2+ years) and I’d like to give it an honest attempt at success before I head another direction.

I’m currently using an Aeotec Z-Stick Gen5 w/ a 5’ USB extension to get it free of obstructions. It’s currently in the middle of an unfinished basement under a 2400 sq ft house.

The network seems to have high latency with 11 mains and 7 battery power devices. The mains are almost all in wall, but no metal or other obvious obstructions. Should I be expecting that most all mains should be neighbors with each other? For example, I have 2 mains devices 30’ literally line of sight and they don’t show each other as neighbors. I’m not sure how mature the ‘Health Check’ is in Z-Ware JS, but a node that is 4 feet line of sight from my controller gets a 5/10 rating, no failed pings but latency is all 130ms+.

Any and all help / recommendations is welcome!