For me it depends on the shoe. If it's something that doesn't work for me skateboarding, I'll try to repurpose it for some other use, or if the condition is still close enough to new, donate it to a secondhand store. I currently have a few slip-ons (vulc and cupsole) that are change of pace, non-work, non-skate shoes. I also have a few pairs of low cut cupsoles that I throw a second insole into and wear to work. This is how shoe collections get out of control.
If it is something I really like and know I won't be able to get again (the Ben Raemers Converse, the 2020 Hi How Are You? Project Slip-Ons, the Austin FC Gazelles), it goes in my closet and rarely sees the light of day.
If it's a skate shoe that works for me, I'll superglue the outer facing seams down, and also shoe goo some reinforcement patches to the higher abrasion areas, to keep those going for as long as I can. Usually when the outsole finally loses tread in that spot where the ball of my front foot is, I know it's time to take them to the used shoe donation bin at my local Nike Outlet. I like that bin because they take shoes of all makes and models and grind down the remains to make sport courts and running tracks for underserved communities: That's better than sending them to a landfill.
But yeah, I'm trying to get 4 months out of the shoes I skate in (I'm lucky if I get to skate twice a week for 1.5 hours each session), and then 6 months out of the skate shoes I wear to work. When my work shoes start tearing along the inner part of the heels (when chunks of that padding start breaking off), that's when I replace them.