Yeah, it really depends on a lot of factors, so it's not like there's one supreme answer.

Where I live now, which is a rural area, there's basically nothing within a viable walking distance aside from neighbors. Even then, there are no walkways or sidewalks between houses/properties, so I would be taking my life into my own hands (for those not familiar, that's an idiom) to walk along the roadway to another house. And yes, we've literally had people get hit by vehicles and die out here while walking on/along the roads.

When I lived in suburban and urban areas, my tolerance for walking places was much higher as longer, weather permitting. When I lived off campus during my college years, for example, I didn't mind walking 45 - 60 minutes to get to campus. And if I was having car trouble, it wasn't uncommon for me to walk that much or more to get to a grocery store or the mechanic's shop.

I don't know how representative my preferences are for the rest of the USA, but I live in a dense city.

I have a bicycle (and my city has plenty of bikeshare rentals scattered all throughout) so I'm usually not willing to walk more than 10 minutes.

When the weather is nice, I will walk within 5 minutes (roughly 0.25 miles or 0.5 km), bike within 30 minutes (roughly 5 miles/8km, depending on lights and traffic), and drive or Uber/Lyft beyond that.

When the weather is bad, I usually take mass transit if I can do it with less than 2 transfers, or I'll drive/Uber/Lyft otherwise.

My choice between driving and Uber/Lyft is usually driven by some combination of cost (including parking), convenience, and whether I intend to drink.

I will walk only if getting a couple of things, about a mile or so? Electric bike if 2 bags or less and it's a nice day. Car for weekly shopping, better store 5 miles or so, sadly my path home from work on bike doesn't pass any grocery.

I don't understand the question. You're asking how far a walk is too long before I consider alternate transit? Or how long before I require alternate transit?

If the first, seven minutes.

If the latter, about four hours.

When I was younger, maybe fifteen minutes for small things, like could fit in a backpack.

Past that, I would have better things to do with my time.

Now? Fuck that noise, my crippled ass isn't going to walk to a store at all. Not worth the pain.

Even as a kid, with no real time crunches, twenty minutes was about it because past that you were either outside of town going one direction, or past downtown where the stores were, but that's a different issue lol.

When I lived in a city, it wasn't a great one for walking in the area I had a place. There were/are sections it was realistic, but I couldn't afford them.

I used to live about 10 min walk (uphill) from a grocery store, but would drive if I needed to buy a full weeks worth of groceries. If it was something small, I would walk.

I'd say 15 minutes generally, but it really depends on what the walk is like. If it's a loud busy stroad, I'd only tolerate maybe 5 minutes. If it's a nice quiet pedestrian-focused walkway, I'd bump that up to 30 minutes.