After reading through it all, I think this is more a condemnation of the author's diagram (or at least their decision to put that particular one up-front), than of their process in general, nor the challenge.

Breakdown of (my) issues with the diagram:

- author's interaction with each device is explicitly included, adding unnecessary noise

- "partial" and "full" real-time sync are shown as separate processes, whereas there's no obvious need to differentiate them in such a high-level overview

- devices with "partial" and "full" sync (see above) are colour-coded differently; again differentiation unnecessary

- including onsite & off-site backups in the same diagram is cool but would probably be nicer living in a dedicated backup diagram for better focus

Here's a simplified version of the same diagram:

                                                   ┌───────────────────┐
    ┌───────────┐                  ┌───────────────►                   │
    │ nextcloud │                  │               │     phone         │
    │ music     │                  │               └───────────────────┤
    │ videos    ◄─────realtime sync├───────────────►                   │
    │ photos    │                  │               │     laptop        │
    │ docs      │                  │               ├───────────────────┤
    │ calendar  │                  │               │                   │
    ├───────────┤                  │               │                   │
    │           │                  ├───────────────►     desktop       │
    │ crm       ◄─────┐            │               │                   │
    │           │     │            │               │                   │
    ├───────────┤     │            │               ├───────────────────┤
    │           │     │            │               │                   │
    │ analytics ◄─────┤            │               │                   │
    │           │     │            └───────────────►                   │
    ├───────────┤     │                            │                   │
    │           │     │                            │                   │
    │ web       │◄── daily sync────────────────────►                   │
    │           │                                  │     synology      │
    ├───────────┤     │                            │                   │
    │           │     │                            │                   │
    │ git       ◄─────┤                            │                   │
    │           │     │                            │                   │
    ├───────────┤     │                            └───────────────────┘
    │           │     │
    │ devtools  ◄─────┘
    │           │
    └───────────┘