A little surprised at how many people say they toss shoes out after a few months.
I typically buy a new pair of walking shoes about once a year. I try to get them at Costco or with a coupon from Big Five -- current pair are slip on sketchers that I got last summer for about $30. I buy a new pair of Birkenstocks for summer wear about every 4-5 years.
Older pairs become wear around the house/garden shoes. My 10 YO Birkenstocks were garden shoes for about 5 years after I stopped wearing them as main warm season shoes -- soles finally delaminated late last summer.
I get a new pair of winter boots every 5 years or so. Like the other types of shoes, the old ones become backups for muckier tasks so that the newer ones last longer.
If you ever need to paint, it is nice to have an old pair of shoes you don't mind getting messed up. If you sometimes do day hikes or beach walks where you have to cross streams, an extra pair of shoes you can throw on temporarily so your main hikers don't get wet is also worth considering. Wouldn't want to lug wet shoes around on an overnight hike, but if you are just out for the day an old pair of runners isn't much extra weight.
Also, there are many ways that shoes and their parts can be recycled. Please consider that option as opposed to sending them to the landfill:
https://www.treehugger.com/shoe-recycling-guide-5194664Oh, another way you can extend the useful life of shoes is to replace the insoles when the originals start to get too worn/squished down