What's the longest you would consider leaving your cat(s) alone, given adequate food, water, and litter? A day? A week? I realize it's not the optimal situation, but what if?
HI. Depends somewhat on your cat's age, demeanor, behavior, how used to is to being left alone at all, not to mention how clean it likes it's litter box, how often it likes/needs to be fed, and whether or not there are means by which to ensure the water is kept clean, and someone to check up on possible health issues arising.
A work day is almost impossible to avoid; but, other than that any more than overnight really requires someone to come in and check on the cat - food, water changes, litterbox clean outs, and company/play time in general.
Not sure what your circumstances are, but typically a friend/family member can tend to these things if you have to be gone longer than that. Worse case scenario, you pay someone to do it - after interviewing them and having the cat meet the sitter. It can even be a neighbor kid whom you are familiar with.
In my younger, less cat-knowledgeable days, I might have done it - although I can't recall doing so. But, now, no more.
I never left my cat and dog longer than a day. I usually ask for my family/friends help to look out for them whenever I go on a vacation. They do have their own automatic feedersand waterers yet I don't think that it is fine to leave these two furs of mine alone. I feel at ease knowing that someone is taking good care of them whenever I am not around.