Due to my pre-retirement profession, I was a part of dealing with the cleanup of a few hundred situations where someone died alone at home or all the residents of the home died during the same incident. Some went to sleep and didn’t wake up. Some accidental drug overdoses. Some suicides and murder/suicides.
The way the deceased folks were discovered varied, but pretty much fell into three categories. Earliest discovery (and most popular with the cases I dealt with) was usually someone they were regularly in contact with noticed their absence and checked on them themselves or via law enforcement welfare check. They didn’t show up for work, didn’t respond to a friend’s daily phone call, didn’t show up for lunch at the restaurant they ate at every day, etc.
Second most popular method of discovery was neighbors smelled something bad, it got worse over a few days, and they started investigating the source. Usually that was in a neighborhood or multi-family dwelling.
Last was mail piling up, bills going unpaid, and eventually in the course of someone trying to collect on those unpaid bills they realized their collection target might be deceased which caused them to call law enforcement for a welfare check. That one could take a while, but when the unpaid bills resulted in a personal visit to the residence (posting notice before shutting off power, mail deliverer walks up to front door to look around due to mail piled up, etc.) the smell often resulted in a law enforcement visit.
As best I recall, the longest anyone went undiscovered on anything I was involved with was estimated at 6 months based on a variety of information. That was an elderly lady who was quite isolated to the point of near hermit status. Most all bills were on auto pay. Only income was social security that auto deposited. So her relatively simple financial life continued rolling despite her demise. Eventually, the property got to looking so neglected people in the community got to discussing when was the last time anyone saw her, which led to a welfare check.
I guess the point of that is if you live alone and it matters to you how long your body would be left unattended after your spirit has departed, you about have to have at least one person that will go looking for you if you don’t communicate with them for a couple days even if it’s just a “good morning” text and response to verify you’re both still alive.