I keep one of each tool in my inventory. If I anticipate a tool (mainly axe or stone axe) being broken then I'll make another one and carry it as well so that way I can quickly switch to it when needed.
One of each, unless I'm going to be focusing on a specific task: like arranging flowers = extra shovel. And so on if I feel like a tool is coming to close to breaking, i customize it ASAP!
I keep one of each with me! I play at night a lot though, and don’t love to continuously craft more tools. Because of that, I buy extras and keep them on benches in my crafting workshop area so that I can grab them.
One of each is enough for me to carry as I'm doing my chores everyday. I keep a work bench outside along with some materials on the ground in case one of my tools breaks, I don't mind making more. Though sometimes I do carry more than one fishing rod or bug net if I'm doing one of those activities, but most of the time it's just one of each.
Shovel, net, fishing rod, vaulting pole, and ladder are always on hand. Even if I don’t use the vaulting pole or ladder much anymore sometimes they still come in handy for short cuts. I leave my watering can at home because I don’t breed hybrids actively anymore. I take my axe out when I need it for a nook mile+ task only, or I just craft a flimsy axe on the spot.
I keep one of everything, including two types of axes, except for a wand and vaulting pole. Since I unlocked terraforming I haven’t needed to use a pole to clear rivers. And during the one day I was TTing I got so sick of undoing my wand outfits and redoing them just to visit the Able Sisters I decided to drop the wand altogether. Haven’t picked it up since
Rn I think I have one of everything, including the wand and the watering can, but I've put my stone axe & ocarina down somewhere since I really don't use them much atm. I think I use my tools enough to justify carrying a DIY bench & customization kits everywhere and i'm too lazy to do it anyway oops
One of each. I could ditch the vaulting pole because I have bridges or stepping stones everywhere, but I can't get to one cliff top or my secret beach without a ladder so I need the ladder. Occasionally I'll have an extra of one but not usually. If I'm going island hopping, I bring at least 10 branches, 4 ore, 5 hardwood, and 3 regular wood in case one of my tools breaks. I've gotten caught not being able to upgrade because I didn't get the right resources to make and upgrade a tool before the tool to get those resources breaks a couple too many times.
I only keep one of each in my pocket unless I am doing a massive catching bugs/fish or flower transplanting then I have two. I also have several tools crafted of each that I keep in my storage for speed sake.