> Are you advocating buying internet service from two different companies and paying for both every month in case one fails for a brief period of time?

That's not an unreasonable solution, considering most people already pay two ISPs (one fixed, and another for their phone/tablet). When your home wifi goes down, you're going to fall-back to your mobile anyway. I'm thinking of getting an extra data SIM, an LTE modem and do auto-failover.

--edit--

My needs are somewhat unique - my traveling laptop is on its last legs (and will be replaced by a cheap chromebook. Desktops/servers get better bang for the buck compared to laptops. Go figure!), so I tunnel onto a server at home for heavy-lift computing. If the internet fails when I'm not home, I'd be left stranded (and this has happened).

In my case my Surface Book 2 gives me all the firepower I need to not miss my desktop, and it also has a PCIE SSD on it like my desktop. I do agree, sometimes tethering is highly useful, at least in my case on my laptop. I try to keep as many things as offline capable as possible.

That's literally what the author of the article describes.

From a practical point of view I think it's silly to do such a thing for a residential situation, but I can appreciate using it as a learning experience for building systems like this.

Depends how reliable your isp is ans how much it costs if it goes down.

3g is good enough backup for me, but for the office we go for two routers two isps and vrrp on the lan side, load balance across the wans, with failover to the other one.