Requirements and needs are always a matter in any case.
If you havnt got any requirements or needs, there are no obvious reason for making any kind of insurances (having a backup strategy) for it. This goes for general matters.
In this particular situation, we´re talking about smarthome system, which (as I said) are suppose to be running 24/7. It means, (I have to make some assumptions for most people), that there is some kind of an need and requirements, unless your run your smarthome system just for fun.
Every kind of strategy got cons and pros. And particular backup strategies can/will often be filled with compromises. wether its about equipments or time, there will probably be compromises.
Every compromise has a consequence.
In order to decide those compromises, the user have to know the consequence.
Not knowing the consequences, the chances are that the user will pick the wrong compromises.
In my world, the best way to find the compromises is by the use of one single question - “What if…” And then use this question in all thinkable situations. Like:
What if my house burns down to the ground? - Well, simple, there is no need to have a backup for my smarthome system, cause there is no longer a house. I could have a backup though, cause my house is probably beeing rebuild. But this backup would then be used to rebuild everything from scratch, and probably no directly useable in the new house, which might be build differently.
A more realistic case could be:
What if my SD card in my Rpi crash? - There are several solution for this. But first you need to decide, if you even want to recreate your system or not. In this case I assume you want to.
So you´ll need to recreate your SD card, maybe even buying a new SD card first. Unfortunatly this crash happened at a time, where it takes a few days to get a new SD card. Can you live with that? If not, then you need to decide how long you want to wait. Ideally you would already have a spare SD card to use, which minimize the down time of your system. If not, your have to wait.
Now you got this spare SD card, you need to decide wether you want to start all over recreating everything, or if you have a backup file, which you can restore fast. Again, this is a matter of down time. If you need to recreate everything from scratch, then down time will rise alot more than having a backup you just need to restore.
These are all quite simple decisions to make. But they´re important to know the consequences and to build your strategy.
Lets take this a bit futher:
What if my Rpi breaks? - This is where the compromises starts rolling in. Equipments is a though one to decide. Ideally you would have a spare parts of everything. But thats often not possible due to the financial situation/echonomic. So this is where a true compromises will appear for most.
If you cant afford a new Rpi, then the consequence is pretty simple - You no longer have a smarthome system.
If you can afford a new Rpi, but need to buy one first, the consequence is more down-time.Can you live with that? If not, then your strategy means you either have to have a spare Rpi ready, or make sure you can get one when the main Rpi breaks. Its just a question of down-time vs needs.
What if my internet connection drops?
Well - Can you live without? If not, there is only one true solution - Get a spare internet connection, and maybe new network equipments which is capable of using redundant internet, (this could be OTA 3G/4G/5G internet).
Maybe you dont know if you can live without. Maybe you have some services running where the need of internet isnt that important. And the rest of the system works just fine without internet. In this case you dont need a spare internet connection. But you´ll have to ask yourself for each services running, can you live without.
This is the way I build my strategy, simply by simply asking myself, “What if…” questions, and knowing the consequences on each answer.
I hope it makes some sense.
There is however one single question which infact isnt important to you, but to the rest of your family in your house… “What about your family if you die?”
I´ll not borring you with more writings on this, but just leave you with a small youtube movie, where a person (Jonathan) from SuperhouseTV explains how he deals with it, and why he thinks its important. I do share his opinion, but I have to admit, I have not done this myself, yet.