I used to do quite a lot of freelance work just to make some extra money and I agree, some home / residential work really can be Heartbreak Hotel.
That said, they weren’t all bad, maybe 1 in 5 jobs would be a nightmare, take far longer than anticipated, run in to endless complications, and then you’re faced with the issue, as others have pointed out, that you can’t charge a residential customer hundreds because a scan took hours to complete.
For that kind of work I’d recommend having a base set price, and advise the customer up front ‘I charge X for this service, although if it runs into problems we may need to revise it a little’. That way they get a ballpark figure, and aren’t worried about the hours clocking up, but equally won’t baulk if you turn round later and say ‘This has went sideways, I’m going to have to charge a little extra’.
The problem with residential is the sheer volume of unknowns. Sure this can and does happen in a business environment but it’s far more likely in a home where you have god knows what mixture of random hardware, old and new, screwed up networks, malware riddled devices, the list goes on and on. It’s this kind of thing that makes what should be a 10 minute job turn into 4 hours.
Business is somewhat easier, you can either charge an hourly rate, or again have a fixed price for certain services. The difference is they will have a greater commercial understanding of the cost of your time and won’t be shocked if you present them with a bill for a few hundred.
Residential jobs, do them by all means, there’s money to be made certainly, but go into it with your eyes open, you will, on occasion, work very hard for that money.